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Solved Problems

In my spare time I enjoy solving programming puzzles, often algorithmic or mathematical in nature. Here is an automatically updated list of the problems I’ve solved on some of my favorite online judges. In total there are 2902 problems listed below.

Project Euler
Project Euler is probably the reason I started enjoying mathematics and solving mathematical problems in the first place. It has a lot of very high quality mathematical problems, and a new problem is added almost weekly. I’m currently the highest ranked Project Euler member from Iceland.

SuprDewd on Project Euler

Solved problems (412)
  • Problem 1: Multiples of 3 and 5
  • Problem 2: Even Fibonacci numbers
  • Problem 3: Largest prime factor
  • Problem 4: Largest palindrome product
  • Problem 5: Smallest multiple
  • Problem 6: Sum square difference
  • Problem 7: 10001st prime
  • Problem 8: Largest product in a series
  • Problem 9: Special Pythagorean triplet
  • Problem 10: Summation of primes
  • Problem 11: Largest product in a grid
  • Problem 12: Highly divisible triangular number
  • Problem 13: Large sum
  • Problem 14: Longest Collatz sequence
  • Problem 15: Lattice paths
  • Problem 16: Power digit sum
  • Problem 17: Number letter counts
  • Problem 18: Maximum path sum I
  • Problem 19: Counting Sundays
  • Problem 20: Factorial digit sum
  • Problem 21: Amicable numbers
  • Problem 22: Names scores
  • Problem 23: Non-abundant sums
  • Problem 24: Lexicographic permutations
  • Problem 25: 1000-digit Fibonacci number
  • Problem 26: Reciprocal cycles
  • Problem 27: Quadratic primes
  • Problem 28: Number spiral diagonals
  • Problem 29: Distinct powers
  • Problem 30: Digit fifth powers
  • Problem 31: Coin sums
  • Problem 32: Pandigital products
  • Problem 33: Digit cancelling fractions
  • Problem 34: Digit factorials
  • Problem 35: Circular primes
  • Problem 36: Double-base palindromes
  • Problem 37: Truncatable primes
  • Problem 38: Pandigital multiples
  • Problem 39: Integer right triangles
  • Problem 40: Champernowne's constant
  • Problem 41: Pandigital prime
  • Problem 42: Coded triangle numbers
  • Problem 43: Sub-string divisibility
  • Problem 44: Pentagon numbers
  • Problem 45: Triangular, pentagonal, and hexagonal
  • Problem 46: Goldbach's other conjecture
  • Problem 47: Distinct primes factors
  • Problem 48: Self powers
  • Problem 49: Prime permutations
  • Problem 50: Consecutive prime sum
  • Problem 51: Prime digit replacements
  • Problem 52: Permuted multiples
  • Problem 53: Combinatoric selections
  • Problem 54: Poker hands
  • Problem 55: Lychrel numbers
  • Problem 56: Powerful digit sum
  • Problem 57: Square root convergents
  • Problem 58: Spiral primes
  • Problem 59: XOR decryption
  • Problem 60: Prime pair sets
  • Problem 61: Cyclical figurate numbers
  • Problem 62: Cubic permutations
  • Problem 63: Powerful digit counts
  • Problem 64: Odd period square roots
  • Problem 65: Convergents of e
  • Problem 66: Diophantine equation
  • Problem 67: Maximum path sum II
  • Problem 68: Magic 5-gon ring
  • Problem 69: Totient maximum
  • Problem 70: Totient permutation
  • Problem 71: Ordered fractions
  • Problem 72: Counting fractions
  • Problem 73: Counting fractions in a range
  • Problem 74: Digit factorial chains
  • Problem 75: Singular integer right triangles
  • Problem 76: Counting summations
  • Problem 77: Prime summations
  • Problem 78: Coin partitions
  • Problem 79: Passcode derivation
  • Problem 80: Square root digital expansion
  • Problem 81: Path sum: two ways
  • Problem 82: Path sum: three ways
  • Problem 83: Path sum: four ways
  • Problem 84: Monopoly odds
  • Problem 85: Counting rectangles
  • Problem 86: Cuboid route
  • Problem 87: Prime power triples
  • Problem 88: Product-sum numbers
  • Problem 89: Roman numerals
  • Problem 90: Cube digit pairs
  • Problem 91: Right triangles with integer coordinates
  • Problem 92: Square digit chains
  • Problem 93: Arithmetic expressions
  • Problem 94: Almost equilateral triangles
  • Problem 95: Amicable chains
  • Problem 96: Su Doku
  • Problem 97: Large non-Mersenne prime
  • Problem 98: Anagramic squares
  • Problem 99: Largest exponential
  • Problem 100: Arranged probability
  • Problem 101: Optimum polynomial
  • Problem 102: Triangle containment
  • Problem 103: Special subset sums: optimum
  • Problem 104: Pandigital Fibonacci ends
  • Problem 105: Special subset sums: testing
  • Problem 106: Special subset sums: meta-testing
  • Problem 107: Minimal network
  • Problem 108: Diophantine reciprocals I
  • Problem 109: Darts
  • Problem 110: Diophantine reciprocals II
  • Problem 111: Primes with runs
  • Problem 112: Bouncy numbers
  • Problem 113: Non-bouncy numbers
  • Problem 114: Counting block combinations I
  • Problem 115: Counting block combinations II
  • Problem 116: Red, green or blue tiles
  • Problem 117: Red, green, and blue tiles
  • Problem 118: Pandigital prime sets
  • Problem 119: Digit power sum
  • Problem 120: Square remainders
  • Problem 121: Disc game prize fund
  • Problem 122: Efficient exponentiation
  • Problem 123: Prime square remainders
  • Problem 124: Ordered radicals
  • Problem 125: Palindromic sums
  • Problem 126: Cuboid layers
  • Problem 127: abc-hits
  • Problem 128: Hexagonal tile differences
  • Problem 129: Repunit divisibility
  • Problem 130: Composites with prime repunit property
  • Problem 131: Prime cube partnership
  • Problem 132: Large repunit factors
  • Problem 133: Repunit nonfactors
  • Problem 134: Prime pair connection
  • Problem 135: Same differences
  • Problem 136: Singleton difference
  • Problem 137: Fibonacci golden nuggets
  • Problem 138: Special isosceles triangles
  • Problem 139: Pythagorean tiles
  • Problem 140: Modified Fibonacci golden nuggets
  • Problem 141: Investigating progressive numbers, <i>n</i> , which are also square
  • Problem 142: Perfect Square Collection
  • Problem 143: Investigating the Torricelli point of a triangle
  • Problem 144: Investigating multiple reflections of a laser beam
  • Problem 145: How many reversible numbers are there below one-billion?
  • Problem 146: Investigating a Prime Pattern
  • Problem 147: Rectangles in cross-hatched grids
  • Problem 148: Exploring Pascal's triangle
  • Problem 149: Searching for a maximum-sum subsequence
  • Problem 150: Searching a triangular array for a sub-triangle having minimum-sum
  • Problem 151: Paper sheets of standard sizes: an expected-value problem
  • Problem 152: Writing 1/2 as a sum of inverse squares
  • Problem 153: Investigating Gaussian Integers
  • Problem 154: Exploring Pascal's pyramid
  • Problem 155: Counting Capacitor Circuits
  • Problem 156: Counting Digits
  • Problem 157: Solving the diophantine equation <sup>1</sup> / <sub><var>a</var></sub> + <sup>1</sup> / <sub><var>b</var></sub> = <sup><var>p</var></sup> / <sub>10<sup><var>n</var></sup></sub>
  • Problem 158: Exploring strings for which only one character comes lexicographically after its neighbour to the left
  • Problem 159: Digital root sums of factorisations
  • Problem 160: Factorial trailing digits
  • Problem 161: Triominoes
  • Problem 162: Hexadecimal numbers
  • Problem 164: Numbers for which no three consecutive digits have a sum greater than a given value
  • Problem 165: Intersections
  • Problem 166: Criss Cross
  • Problem 167: Investigating Ulam sequences
  • Problem 168: Number Rotations
  • Problem 169: Exploring the number of different ways a number can be expressed as a sum of powers of 2
  • Problem 170: Find the largest 0 to 9 pandigital that can be formed by concatenating products
  • Problem 171: Finding numbers for which the sum of the squares of the digits is a square
  • Problem 172: Investigating numbers with few repeated digits
  • Problem 173: Using up to one million tiles how many different "hollow" square laminae can be formed?
  • Problem 174: Counting the number of "hollow" square laminae that can form one, two, three, … distinct arrangements
  • Problem 175: Fractions involving the number of different ways a number can be expressed as a sum of powers of 2
  • Problem 176: Right-angled triangles that share a cathetus
  • Problem 177: Integer angled Quadrilaterals
  • Problem 178: Step Numbers
  • Problem 179: Consecutive positive divisors
  • Problem 180: Rational zeros of a function of three variables
  • Problem 181: Investigating in how many ways objects of two different colours can be grouped
  • Problem 182: RSA encryption
  • Problem 183: Maximum product of parts
  • Problem 185: Number Mind
  • Problem 186: Connectedness of a network
  • Problem 187: Semiprimes
  • Problem 188: The hyperexponentiation of a number
  • Problem 189: Tri-colouring a triangular grid
  • Problem 190: Maximising a weighted product
  • Problem 191: Prize Strings
  • Problem 192: Best Approximations
  • Problem 193: Squarefree Numbers
  • Problem 194: Coloured Configurations
  • Problem 195: Inscribed circles of triangles with one angle of 60 degrees
  • Problem 196: Prime triplets
  • Problem 197: Investigating the behaviour of a recursively defined sequence
  • Problem 199: Iterative Circle Packing
  • Problem 200: Find the 200th prime-proof sqube containing the contiguous sub-string "200"
  • Problem 201: Subsets with a unique sum
  • Problem 202: Laserbeam
  • Problem 203: Squarefree Binomial Coefficients
  • Problem 204: Generalised Hamming Numbers
  • Problem 205: Dice Game
  • Problem 206: Concealed Square
  • Problem 207: Integer partition equations
  • Problem 208: Robot Walks
  • Problem 209: Circular Logic
  • Problem 211: Divisor Square Sum
  • Problem 213: Flea Circus
  • Problem 214: Totient Chains
  • Problem 215: Crack-free Walls
  • Problem 216: Investigating the primality of numbers of the form 2 <var>n</var> <sup>2</sup> -1
  • Problem 217: Balanced Numbers
  • Problem 218: Perfect right-angled triangles
  • Problem 219: Skew-cost coding
  • Problem 220: Heighway Dragon
  • Problem 221: Alexandrian Integers
  • Problem 222: Sphere Packing
  • Problem 225: Tribonacci non-divisors
  • Problem 226: A Scoop of Blancmange
  • Problem 227: The Chase
  • Problem 228: Minkowski Sums
  • Problem 229: Four Representations using Squares
  • Problem 230: Fibonacci Words
  • Problem 231: The prime factorisation of binomial coefficients
  • Problem 232: The Race
  • Problem 233: Lattice points on a circle
  • Problem 234: Semidivisible numbers
  • Problem 235: An Arithmetic Geometric sequence
  • Problem 237: Tours on a 4 x n playing board
  • Problem 239: Twenty-two Foolish Primes
  • Problem 240: Top Dice
  • Problem 242: Odd Triplets
  • Problem 243: Resilience
  • Problem 244: Sliders
  • Problem 248: Numbers for which Euler’s totient function equals 13!
  • Problem 249: Prime Subset Sums
  • Problem 250: 250250
  • Problem 253: Tidying up
  • Problem 259: Reachable Numbers
  • Problem 263: An engineers' dream come true
  • Problem 265: Binary Circles
  • Problem 266: Pseudo Square Root
  • Problem 267: Billionaire
  • Problem 268: Counting numbers with at least four distinct prime factors less than 100
  • Problem 269: Polynomials with at least one integer root
  • Problem 271: Modular Cubes, part 1
  • Problem 272: Modular Cubes, part 2
  • Problem 273: Sum of Squares
  • Problem 274: Divisibility Multipliers
  • Problem 276: Primitive Triangles
  • Problem 277: A Modified Collatz sequence
  • Problem 278: Linear Combinations of Semiprimes
  • Problem 279: Triangles with integral sides and an integral angle
  • Problem 280: Ant and seeds
  • Problem 281: Pizza Toppings
  • Problem 282: The Ackermann function
  • Problem 284: Steady Squares
  • Problem 286: Scoring probabilities
  • Problem 287: Quadtree encoding (a simple compression algorithm)
  • Problem 288: An enormous factorial
  • Problem 290: Digital Signature
  • Problem 291: Panaitopol Primes
  • Problem 292: Pythagorean Polygons
  • Problem 293: Pseudo-Fortunate Numbers
  • Problem 294: Sum of digits – experience #23
  • Problem 297: Zeckendorf Representation
  • Problem 301: Nim
  • Problem 302: Strong Achilles Numbers
  • Problem 303: Multiples with small digits
  • Problem 304: Primonacci
  • Problem 306: Paper-strip Game
  • Problem 307: Chip Defects
  • Problem 309: Integer Ladders
  • Problem 310: Nim Square
  • Problem 312: Cyclic paths on Sierpiński graphs
  • Problem 313: Sliding game
  • Problem 315: Digital root clocks
  • Problem 317: Firecracker
  • Problem 320: Factorials divisible by a huge integer
  • Problem 321: Swapping Counters
  • Problem 323: Bitwise-OR operations on random integers
  • Problem 324: Building a tower
  • Problem 326: Modulo Summations
  • Problem 327: Rooms of Doom
  • Problem 329: Prime Frog
  • Problem 333: Special partitions
  • Problem 336: Maximix Arrangements
  • Problem 340: Crazy Function
  • Problem 341: Golomb's self-describing sequence
  • Problem 342: The totient of a square is a cube
  • Problem 343: Fractional Sequences
  • Problem 345: Matrix Sum
  • Problem 346: Strong Repunits
  • Problem 347: Largest integer divisible by two primes
  • Problem 348: Sum of a square and a cube
  • Problem 349: Langton's ant
  • Problem 351: Hexagonal orchards
  • Problem 354: Distances in a bee's honeycomb
  • Problem 357: Prime generating integers
  • Problem 358: Cyclic numbers
  • Problem 359: Hilbert's New Hotel
  • Problem 363: Bézier Curves
  • Problem 364: Comfortable distance
  • Problem 365: A huge binomial coefficient
  • Problem 367: Bozo sort
  • Problem 368: A Kempner-like series
  • Problem 371: Licence plates
  • Problem 375: Minimum of subsequences
  • Problem 377: Sum of digits, experience 13
  • Problem 378: Triangle Triples
  • Problem 379: Least common multiple count
  • Problem 380: Amazing Mazes!
  • Problem 381: (prime-k) factorial
  • Problem 386: Maximum length of an antichain
  • Problem 387: Harshad Numbers
  • Problem 388: Distinct Lines
  • Problem 389: Platonic Dice
  • Problem 390: Triangles with non rational sides and integral area
  • Problem 393: Migrating ants
  • Problem 401: Sum of squares of divisors
  • Problem 407: Idempotents
  • Problem 408: Admissible paths through a grid
  • Problem 411: Uphill paths
  • Problem 412: Gnomon numbering
  • Problem 413: One-child Numbers
  • Problem 416: A frog's trip
  • Problem 417: Reciprocal cycles II
  • Problem 421: Prime factors of <var>n</var> <sup>15</sup> +1
  • Problem 424: Kakuro
  • Problem 425: Prime connection
  • Problem 429: Sum of squares of unitary divisors
  • Problem 430: Range flips
  • Problem 435: Polynomials of Fibonacci numbers
  • Problem 437: Fibonacci primitive roots
  • Problem 441: The inverse summation of coprime couples
  • Problem 442: Eleven-free integers
  • Problem 443: GCD sequence
  • Problem 448: Average least common multiple
  • Problem 451: Modular inverses
  • Problem 452: Long Products
  • Problem 454: Diophantine reciprocals III
  • Problem 457: A polynomial modulo the square of a prime
  • Problem 458: Permutations of Project
  • Problem 461: Almost Pi
  • Problem 463: A weird recurrence relation
  • Problem 464: Möbius function and intervals
  • Problem 467: Superinteger
  • Problem 468: Smooth divisors of binomial coefficients
  • Problem 469: Empty chairs
  • Problem 473: Phigital number base
  • Problem 475: Music festival
  • Problem 479: Roots on the Rise
  • Problem 480: The Last Question
  • Problem 485: Maximum number of divisors
  • Problem 487: Sums of power sums
  • Problem 491: Double pandigital number divisible by 11
  • Problem 493: Under The Rainbow
  • Problem 494: Collatz prefix families
  • Problem 495: Writing n as the product of k distinct positive integers
  • Problem 500: Problem 500!!!
  • Problem 501: Eight Divisors
  • Problem 504: Square on the Inside
  • Problem 506: Clock sequence
  • Problem 509: Divisor Nim
  • Problem 510: Tangent Circles
  • Problem 511: Sequences with nice divisibility properties
  • Problem 512: Sums of totients of powers
  • Problem 514: Geoboard Shapes
  • Problem 516: 5-smooth totients
  • Problem 518: Prime triples and geometric sequences
  • Problem 519: Tricolored Coin Fountains
  • Problem 521: Smallest prime factor
  • Problem 523: First Sort I
  • Problem 524: First Sort II
  • Problem 527: Randomized Binary Search
  • Problem 529: 10-substrings
  • Problem 530: GCD of Divisors
  • Problem 531: Chinese leftovers
  • Problem 533: Minimum values of the Carmichael function
  • Problem 534: Weak Queens
  • Problem 535: Fractal Sequence
  • Problem 536: Modulo power identity
  • Problem 537: Counting tuples
  • Problem 538: Maximum quadrilaterals
  • Problem 539: Odd elimination
  • Problem 540: Counting primitive Pythagorean triples
  • Problem 541: Divisibility of Harmonic Number Denominators
  • Problem 542: Geometric Progression with Maximum Sum
  • Problem 543: Prime-Sum Numbers
  • Problem 544: Chromatic Conundrum
  • Problem 545: Faulhaber's Formulas
  • Problem 546: The Floor's Revenge
  • Problem 548: Gozinta Chains
  • Problem 549: Divisibility of factorials
  • Problem 551: Sum of digits sequence
  • Problem 552: Chinese leftovers II
  • Problem 553: Power sets of power sets
  • Problem 561: Divisor Pairs
  • Problem 565: Divisibility of sum of divisors
  • Problem 571: Super Pandigital Numbers
  • Problem 575: Wandering Robots
  • Problem 581: 47-smooth triangular numbers
  • Problem 582: Nearly isosceles 120 degree triangles
  • Problem 583: Heron Envelopes
  • Problem 601: Divisibility streaks
  • Problem 603: Substring sums of prime concatenations
  • Problem 612: Friend numbers
  • Problem 618: Numbers with a given prime factor sum
  • Problem 625: Gcd sum
  • Problem 628: Open chess positions
  • Problem 630: Crossed lines
  • Problem 631: Constrained Permutations
  • Kattis
    Kattis is currently my favorite online judge. Unfortunately there aren’t many active coders on Kattis, which is a pity since it holds a lot of high quality algorithmic problems. I’m currently the second highest ranked user on Kattis. Also see my profile page.

    Solved problems (1259)
  • 0-1 Sequences
  • 10 Kinds of People
  • 2048
  • 3D Printed Statues
  • 4 thought
  • A1 Paper
  • Aaah!
  • ABC
  • A+B Problem
  • Absurdistan Roads II
  • Absurdistan Roads III
  • A Classy Problem
  • ACM Contest Scoring
  • Adding Words
  • A Different Problem
  • Adjoin the Networks
  • Administrative Difficulties
  • Adventures in Moving — Part IV
  • A Favourable Ending
  • A Feast For Cats
  • Air Conditioned Minions
  • Airline Hub
  • Airports
  • Akcija
  • Aladin
  • Alien Numbers
  • A List Game
  • All about that base
  • All Different Directions
  • All Friends
  • All Just A Dream
  • Almost Perfect
  • Almost Union-Find
  • Alphabet
  • Alphabet Spam
  • Alternative Bracket Notation
  • Amalgamated Artichokes
  • Amanda Lounges
  • Ambiguous Result
  • A Multiplication Game
  • Anagram Counting
  • A New Alphabet
  • Animal Classification
  • An Industrial Spy
  • Another Brick in the Wall
  • Another Candies
  • Anthony and Cora
  • Ants
  • Apaxiaaaaaaaaaaaans!
  • Apparatus
  • Apple Market
  • Aquarium Tank
  • A Rational Sequence
  • A Rational Sequence 2
  • A Rational Sequence (Take 3)
  • Arcade!
  • Arctic Network
  • A Real Challenge
  • Arithmetic
  • Army Strength (Easy)
  • Army Strength (Hard)
  • Arranging Hat
  • Artwork
  • A Safe Bet
  • ASCII Figure Rotation
  • As Easy as CAB
  • Aspen Avenue
  • Assigning Workstations
  • Association for Computing Machinery
  • Association for Control Over Minds
  • Association for the Country of Mububa
  • A Towering Problem
  • Autori
  • Average Speed
  • A Vicious Pikeman (Easy)
  • A Vicious Pikeman (Hard)
  • Avogadro
  • Avoiding the Apocalypse
  • Avoidland
  • A Walk Through The Forest
  • Babelfish
  • Babylonian Numbers
  • Bachet’s Game
  • Backspace
  • Bacon, Eggs, and Spam
  • Bag of Tiles
  • Bakice
  • Balanced Diet
  • Ball Bearings
  • Baloni
  • Bank Queue
  • Bard
  • Barica
  • Base-2 Palindromes
  • BASIC Interpreter
  • Basic Remains
  • Basin City Surveillance
  • Batmanacci
  • Battleship
  • Battle Simulation
  • Beat the Spread!
  • Beavergnaw
  • Beehives
  • Beehives
  • Beekeeper
  • Being Solarly Systematic
  • Bela
  • Bell Ringing
  • Best Compression Ever
  • Best Compromise
  • Best Relay Team
  • Better Productivity
  • Biased Standings
  • Bicikli
  • Big Data
  • Big Truck
  • Bijele
  • Biking Duck
  • Bilateral Projects
  • Billiard
  • Binary search tree
  • Bing It On
  • Birds on a Wire
  • Birthday Party
  • Bishops
  • Bit by Bit
  • Bitcoin Toss
  • Bits
  • Bits Equalizer
  • Blackboard Numbers
  • Black Friday
  • Black Vienna
  • Bless You Autocorrect!
  • Block Crusher
  • Block Game
  • Blocks on Blocks
  • Board Coloring
  • Board Wrapping
  • Boastin’ Red Socks
  • Boat Parts
  • Bob
  • Bobby’s Bet
  • Boggle
  • Boiling Vegetables
  • Bond
  • Book Circle
  • Book Club
  • Booking
  • Booking a Room
  • Borg Boogie
  • Bounding Robots
  • Bowlstack
  • Boxes
  • Brackets
  • BrainFsckVM
  • Branch Assignment
  • Bread Sorting
  • Breaking Bad
  • Brexit
  • Bricks
  • Brick Wall
  • Bridge Automation
  • British Menu
  • Bucket Brigade
  • Budget
  • Buggy Robot
  • Buggy Robot
  • Build Dependencies
  • Building Fences
  • Bumped!
  • Bumper-To-Bumper Traffic
  • Burrows-Wheeler
  • Bus
  • Bus Numbers
  • Bus Tour
  • Busy Schedule
  • Button Bashing
  • Buying Coke
  • Buzzwords
  • Cake
  • Calculating Dart Scores
  • Calculator
  • Calories From Fat
  • Candle Box
  • Candy Distribution
  • Candy Division
  • Canonical Coin Systems
  • Cantina of Babel
  • Cantor
  • Can’t Stop Playing
  • Canvas Painting
  • Card Hand Sorting
  • Card Magic
  • Card Trick
  • Careful Ascent
  • Car Game
  • Carousel Rides
  • Car Trouble
  • Casting Spells
  • Catalan Numbers
  • Catalan Square
  • Cat Coat Colors
  • Catenyms
  • Catering
  • Cat vs. Dog
  • CD
  • Ceiling Function
  • Celebrity Split
  • Cent Savings
  • Cetiri
  • Cetvrta
  • Character Development
  • Charles in Charge
  • Chasing Subs
  • Cheating a Boolean Tree
  • Cheating Luck
  • Checkers
  • Cheering Game
  • Chemicals Monitoring
  • Chess
  • Chess Competition
  • Chess Tournament
  • Chewbacca
  • Chicken Joggers
  • Chinese Remainder
  • Chinese Remainder Theorem (non-relatively prime moduli)
  • Choosing Numbers
  • Chopping Wood
  • Circuit Counting
  • City Destruction
  • City Park
  • Class Picture
  • Classrooms
  • Cleaning Pipes
  • Cliff Walk
  • Clock Breaking
  • Clock Pictures
  • Closest Pair
  • Closest Pair (Uniform)
  • Closest Sums
  • Closing the Loop
  • Coast Length
  • Coci
  • Code Permutations
  • Code Theft
  • Cokolada
  • Cold-puter Science
  • Collapse
  • Collatz Conjecture
  • Collecting Beepers
  • Coloring Graphs
  • Coloring Socks
  • Combination Lock
  • Comma Sprinkler
  • Committee Assignment
  • Common Subexpression Elimination
  • Company Picnic
  • Compensation
  • Compiler
  • Completing the Square
  • Compositions
  • Compound Words
  • Connect
  • Conservation
  • Constrained Freedom of Choice
  • Continued Fraction
  • Conversation Log
  • Convex Hull
  • Convex Polygon Area
  • Cookie Cutters
  • Cookie Selection
  • Cooking Water
  • Copying DNA
  • Councilling
  • Countdown
  • Counting Stars
  • Counting Subsequences (Hard)
  • Count von Walken’s Fence
  • Coverage
  • Covered Walkway
  • Cover up
  • Cow Crane
  • Cracker Barrel Game
  • Cracking RSA
  • Cracking The Safe
  • Crane Balancing
  • Crazy Driver
  • Credit Card Payment
  • Critical Elements
  • Crne
  • Crop Triangles (Easy)
  • Crop Triangles (Hard)
  • Cross
  • Cross Country
  • Cryptographer’s Conundrum
  • Cryptographic Keys
  • Cuckoo Hashing
  • Cudak
  • Curious Cupid
  • Curse the Darkness
  • Curvy Little Bottles
  • Cutting Brownies
  • Cutting Cheese
  • Cycles (Easy)
  • Cycles (Hard)
  • Cyclic Sightseeing
  • Dance Recital
  • Dance Reconstruction
  • Dance Reconstruction (Hard)
  • Dangerous Skiing
  • Dartboard
  • Darts
  • Datum
  • Daydreaming Stockbroker
  • Daylight Saving Time
  • Dead Fraction
  • Death Knight Hero
  • Deathstar
  • Debugging
  • Deduplicating Files
  • Dejavu
  • Delivering Goods
  • Destination Unknown
  • Detailed Differences
  • Dice Betting
  • Dice Cup
  • Dice Game
  • Dictionary Attack
  • Different Distances
  • Digi Comp II
  • Digital display
  • Digit Sum
  • Dinner Bet
  • Diplomacy
  • Dirty Driving
  • Disastrous Downfall
  • Disastrous Downtime
  • Disgruntled Judge
  • Distinctive Character
  • Distributing Ballot Boxes
  • Divide by 100…
  • Dividing Sequence
  • Divisible Subsequences
  • Divisors
  • Domino
  • Dominoes 2
  • Dominos
  • Domino Tiling
  • Doorman
  • Dots and Boxes
  • Double Dealing
  • Draughts
  • Drink Responsibly
  • DRM Messages
  • Dropping Directions
  • Dungeon master
  • Dvaput
  • DVDs
  • Dvoniz
  • Easy Climb
  • Eb Alto Saxophone Player
  • Eco-driving
  • e-Coins
  • Economical Coverage
  • Egypt
  • Eight Queens
  • Eksplozija
  • Election
  • Elegant Showroom
  • Elementary Math
  • Elevator Trouble
  • Eligibility
  • Emergency Contest Running
  • Emptying the Baltic
  • Encoded Message
  • Enemy Division
  • Engineering English
  • Enlarging Hash Tables
  • Entertainment Box
  • Enumerating Brackets
  • Equal Sums (Easy)
  • Equations
  • Equilibrium Mobile
  • Erase Securely
  • Erdős Numbers
  • Erratic Ants
  • Escape from Enemy Territory
  • Esej
  • Estimating the Area of a Circle
  • Estimation
  • Euclidean TSP
  • Euclid’s Game
  • Eulerian Path
  • EvenOdd
  • Event Planning
  • Even Up Solitaire
  • Evolution in Parallel
  • Exact Change
  • Exactly Paired
  • Exam Redistribution
  • Excellent Engineers
  • Exponial
  • Facility Locations
  • Factors
  • Factovisors
  • Factstone Benchmark
  • Fair Division
  • Faktor
  • Falling Apples
  • Falling Mugs
  • Falling Snow
  • False Sense of Security
  • Family DAG
  • Fancy Fence (easy)
  • Fantastic Problem
  • Farey Sequence Length
  • Faulty Robot
  • FBI Universal Control Numbers
  • Feeding the Herrings
  • Fence Orthogonality
  • Fencing Lessons
  • Fenwick Tree
  • Ferry Loading III
  • Ferry Loading IV
  • Fibonacci Tour
  • Fibonacci Words
  • Filip
  • Finding Lines
  • Fire
  • Fire!
  • Fire Station
  • First Orchard
  • FizzBuzz
  • Fleecing the Raffle
  • Flexible Spaces
  • Flight Plan Evaluation
  • Flight Planning
  • Flip Five
  • Flipping Cards
  • Floppy Music
  • Flower Garden
  • Flowery Trails
  • Flow Layout
  • Flow Shop
  • Flying Safely
  • Fly Swatter
  • Folded Map
  • Font
  • Food Review
  • Food Review (Hard)
  • Forest Highway
  • Forever Young
  • Fractal
  • Fractional Lotion
  • Freckles
  • FreeCell
  • Free Desserts
  • Free Goodies
  • Free Weights
  • Freight Train
  • Friday the 13th
  • Fridge
  • Frosh Week
  • Fruit Baskets
  • Frustrated Queue
  • Full Tank?
  • Functional Fun
  • Fun House
  • Funny Games
  • Galactic Collegiate Programming Contest
  • Galactic Warlords
  • Gallup
  • Game of Cards
  • Game Rank
  • Game Strategy
  • Gathering
  • GCDs
  • Gear Changing
  • Gears
  • Genijalac
  • Geppetto
  • Get Off My Lawn!
  • Get Shorty
  • Getting Gold
  • Getting Rid of Coins
  • Getting Through
  • Get to Work
  • GlitchBot
  • Global Warming
  • Goblin Garden Guards
  • God Save the i-th Queen
  • Godzilla
  • Gokigen Naname
  • Goldbach’s Conjecture
  • Gold Bandits
  • Golf Bot
  • Golomb Rulers
  • Good Coalition
  • Good Morning!
  • Goofy Geometry
  • Gopher II
  • Gorillas
  • Grade Curving
  • Grandpa Bernie
  • Grass Seed Inc.
  • GREAT + SWERC = PORTO
  • Green Eggs and Ham
  • Greeting Card
  • Greetings!
  • Gregory the Grasshopper
  • Grid
  • Grid Game
  • Grid MST
  • Growling Gears
  • Gruesome Cave
  • Guessing Camels
  • Guessing Game
  • Guess the Number
  • Guess the Numbers
  • Half a Cookie
  • Hamiltonian Hypercube
  • Hamming Ellipses
  • Hanging Out on the Terrace
  • Happy Happy Prime Prime
  • Happy Telephones
  • Hay Bales
  • Hay Points
  • Height Ordering
  • Heliocentric
  • Hello World!
  • Help!
  • Help a PhD candidate out!
  • Help Roomba Find Himself
  • Herman
  • Hero Power
  • Hexagon Game
  • Hidden Password
  • Hiding Chickens
  • Highest Tower
  • High Score
  • Hilbert Sort
  • Hill Driving
  • Hill Number
  • Hitting the Targets
  • Hole in One
  • Holey N-Queens (Batman)
  • Honeycomb Walk
  • Honey Heist
  • Hopscotch
  • Horror List
  • House of Cards
  • How do Spiders Walk on Water?
  • How many 0’s?
  • How Many Digits?
  • How many squares?
  • Human Cannonball Run
  • Hurricane Danger!
  • Hyacinth
  • iBoard
  • I Can Guess the Data Structure!
  • Icons in the Toolbar
  • ICPC Tutorial
  • Identifying Map Tiles
  • Ignore the Garbage
  • I Hate The Number Nine
  • Image Decoding
  • Image Processing
  • Immortal Porpoises
  • Imperfect GPS
  • Imperial Measurement
  • Import Spaghetti
  • I’m Thinking of a Number
  • Incognito
  • Increasing Subsequence
  • Indoorienteering
  • Infiltration
  • In Or Out
  • Integer Estate Agent
  • Integer Lists
  • Intercept
  • Interesting Integers
  • Intergalactic Mortgage
  • Interval Cover
  • Introspective Caching
  • Invasion
  • Inverse Factorial
  • IQ Test
  • I Repeat Myself I Repeat Myself I Repeat
  • Iron and Coal
  • Ironman
  • Island Buses
  • Island Hopping
  • Islands
  • It Can Be Arranged
  • I’ve Been Everywhere, Man
  • Jabuke
  • Jack and Jill
  • Jack and the Beanbag
  • Jackpot
  • Jailbreak
  • Jednakost
  • Jelly Raid
  • Jez
  • Job Postings
  • Joe is learning to speak
  • Johnny Applesack
  • Jolly Jumpers
  • Judging Moose
  • Judging Troubles
  • Juggler
  • Jug Hard
  • Juice
  • Jumbled Communication
  • Jumbled Compass
  • Jumping Yoshi
  • Jury Jeopardy
  • Just A Few More Triangles!
  • Just a Minute
  • Kamp
  • Karte
  • Kastenlauf
  • Kayaking Trip
  • Keeping the Dogs Apart
  • Kemija
  • KenKen You Do It?
  • Keyboarding
  • Key to Knowledge
  • Killing Aliens in a Borg Maze
  • Kindergarten
  • Kindergarten Excursion
  • King of Spades
  • K-Inversions
  • Kitchen Combinatorics
  • Kitten on a Tree
  • Knapsack
  • Knapsack Collection
  • Knights in Fen
  • Knight’s Trip
  • Knigs of the Forest
  • Kolone
  • Kornislav
  • Krumpirko
  • Kutevi
  • Ladder
  • Ladice
  • Landline Telephone Network
  • Landscaping
  • Lava
  • Lawn Mower
  • LCM Pair Sum
  • Left Beehind
  • Lektira
  • Let’s Meet
  • Lexicography
  • Lifting Walls
  • Lights
  • Linden Mayor System
  • Linear Equation Solver
  • Linear Recurrences
  • Line Segment Distance
  • Line Segment Intersection
  • Line Them Up
  • Linije
  • Locked Treasure
  • Logo
  • Logo 2
  • Longest Increasing Subsequence
  • Loopy Transit
  • Lost In The Woods
  • Low Order Zeros
  • Low Power
  • ls
  • Lucky Numbers
  • Luggage
  • Mafija
  • Magical GCD
  • Magic Checkerboard
  • Mall Mania
  • Manhattan Positioning System
  • Map Colouring
  • Marbles On A Tree
  • March of the Penguins
  • Mars Window
  • Mårten’s Theorem
  • Matchsticks
  • Mathemagicians
  • Math Worksheet
  • Матрёшка
  • Matrix Inverse
  • Maximal Sequences
  • Maximizing (And Minimizing) Your Winnings
  • Maximum Flow
  • Maximum Loot
  • Maximum Number of Colinear Points
  • Maximum Rent
  • Maze Movement
  • Maze Reduction
  • Measuring Problem Difficulty
  • Mega Inversions
  • Memory Game
  • Memory Match
  • Meow Factor
  • Messages from Outer Space
  • Metaprogramming
  • Mia
  • Milestone Counter
  • Millionaire Madness
  • Minimum Cost Maximum Flow
  • Minimum Cut
  • Minimum Scalar Product
  • Minimum Spanning Tree
  • Mirror Images
  • Misa
  • Mixed-Base Arithmetic
  • Mixed Fractions
  • Mixing Colours
  • Modular Arithmetic
  • Modulo
  • Molekule
  • Money Matters
  • Money Transfers
  • Moogle
  • Mosquito Multiplication
  • Mountain Biking
  • Mountain Scenes
  • Movie collection
  • Moving Pianos
  • Moving to Nuremberg
  • Mravi
  • Mravi
  • Muddy Hike
  • Multigram
  • Multi-Touch Gesture Classification
  • Music Your Way
  • Muzicari
  • Name That Permutation
  • Narrow Art Gallery
  • Nasty Hacks
  • Natjecanje
  • Natrij
  • Necklace Decomposition
  • Nekameleoni
  • Nested Dolls
  • Nice Numbers
  • Nikola
  • Nimionese
  • Nine Knights
  • Nine Packs
  • nnnnn
  • No Duplicates
  • Non-boring sequences
  • Non-negative Partial Sums
  • Not Amused
  • No Trees But Flowers
  • N-Puzzle
  • NTNU Orienteering
  • Number Anagrams
  • Number Fun
  • Numbers
  • Number Sets
  • Number Sets (Hard)
  • Numbers On a Tree
  • Number Trick
  • Ocean Currents
  • Ocean’s Anti-11
  • Ocean’s Anti-11 (Hard)
  • Odd and Even Zeroes
  • Odd Binomial Coefficients
  • Odd Gnome
  • Oddities
  • Odd Man Out
  • Odds of Mia
  • Office Space
  • Oil
  • Oktalni
  • Okvir
  • Okviri
  • Older Brother
  • One Chicken Per Person!
  • Ones
  • Opening Ceremony
  • Open Source
  • Orderly Class
  • Organising the Organisation
  • Ornaments
  • Outer Space Invaders
  • Outing
  • Out of Context
  • Pachyderm Peanut Packing
  • Paintball
  • Paintball II
  • Painting a Fence
  • Paintings
  • Pairing Socks
  • Palindrome Names
  • Palindromes in crosswords
  • Palindrome Substring
  • Palindromic Naming
  • Panda Chess
  • Paradox With Averages
  • Paradox With Averages (Hard)
  • Parking
  • Parking
  • Parovi
  • Parsing Hex
  • Partial Linear Equation Solver
  • Particle Swapping
  • Pascal
  • Pascal’s Hyper-Pyramids
  • Pasijans
  • Password Hacking
  • Passwords
  • Patuljci
  • Patuljci
  • Paul Eigon
  • Pebble Solitaire
  • Pebble Solitaire
  • Peculiar primes
  • Peg
  • Peg Solitaire
  • Peragrams
  • Perfect Pth Powers
  • Performance Review
  • Perica
  • Periodic Strings
  • Perket
  • PermRLE
  • Permutation Encryption
  • Permuted Arithmetic Sequence
  • Persistent Numbers
  • Pervasive Heart Monitor
  • Pesky Mosquitoes
  • Pet
  • Phone List
  • Physical Music
  • Pianino
  • Piece It Together
  • Pieces of Parentheses
  • Pig Latin
  • Pinball
  • Pivot
  • Pizza Crust
  • Pizza Delivery
  • Pizza Hawaii
  • Pizza Problems
  • Plane Ticket Pricing
  • Planina
  • Planting Trees
  • Playground
  • Playing with Geometry
  • Please, Go First
  • Plotting Polynomials
  • Poetry Tower
  • Point in Polygon
  • Pokeball Fever
  • Poklon
  • Polish Notation
  • Pollution Solution
  • Polly Gone
  • Polygon Area
  • Polynomial Multiplication 1
  • Polynomial Multiplication 2
  • Poplava
  • Popular Vote
  • Pork Barrel
  • Postal Delivery
  • Posterize
  • Pot
  • Powers and Modulus
  • Power Signs
  • Power Strings
  • Preludes
  • Pretty Good Cube Root
  • Primal Partitions
  • Primal Representation
  • Primary Register
  • Prime Matrix
  • Prime Path
  • Prime Reduction
  • Prime Sieve
  • Prime Spiral
  • Primonimo
  • Prince and Princess
  • Printing Costs
  • Pripreme
  • Private Space
  • Programming Team
  • Programming Tutors
  • Progressive Scramble
  • Promotions
  • Proving Equivalences
  • Prsteni
  • Prva
  • Pseudoprime numbers
  • Ptice
  • Pub-lic Good
  • Putovanje
  • Quadrant Selection
  • Quadratic Residues
  • Quantum
  • Quantum Superposition
  • Quick Brown Fox
  • Quick Estimates
  • Quite a Problem
  • R2
  • Racetrack
  • Racing Gems
  • Radar
  • Radio Commercials
  • Radio Receiver
  • Radio Transmission
  • Ragged Right
  • Railroad
  • Railway
  • Rainbow Trees
  • Rain Fall
  • Random Walking
  • Rasterized Lines
  • Rational Arithmetic
  • RATS
  • Reachable Roads
  • Reactivity Series
  • Reconnaissance
  • Recount
  • Rectilinear Polygon
  • Recursion + Rand = !Fun
  • Red/Blue Spanning Tree
  • Relatives
  • Repeated Substrings
  • Repeating Decimal
  • Reseto
  • Restaurant Orders
  • Restaurant Ratings
  • Reversed Binary Numbers
  • Reverse Rot
  • Reversing Roads
  • Rhombinoes
  • Ricochet Robots
  • Riječi
  • Rimski
  • Rings
  • Ringworld
  • Risk
  • Road Times
  • Road Work
  • Robert Hood
  • Robot in a Maze
  • Robotopia
  • Robots
  • Robots on a Grid
  • Rock Band
  • Rock-Paper-Scissors Tournament
  • Rock, Scissors, Paper
  • Roller Coaster Fun
  • Room Assignments
  • Rotate and Cut
  • Rubik’s Revenge in … 2D!? 3D?
  • Running MoM
  • Running Steps
  • Sabor
  • Safe Passage
  • Safe Racing
  • Safety in Numbers
  • Saint John Festival
  • Santa Klas
  • Savez
  • Saving Daylight
  • Saving For Retirement
  • Saving the Universe
  • Science!
  • Scrolling Sign
  • Sculpture
  • Secret Chamber at Mount Rushmore
  • Secret Message
  • Secret Santa
  • Secure Doors
  • Self-Assembly
  • Self-Similar Strings
  • Selling Land
  • Semafori
  • Semi-prime H-numbers
  • Sensor Network
  • Sentry Robots
  • Server
  • Set!
  • SETI
  • Setnja
  • Settlers of Catan
  • Seven Wonders
  • Sheba’s Amoebas
  • Sheldon Numbers
  • Shibuya Crossing
  • Ship Traffic
  • Shoot-out
  • Shopaholic
  • Shopping Malls
  • Shopping Plan
  • Shovelling Snow
  • Sibice
  • Sideways Sorting
  • Sierpiński Circumference
  • Sign Profile
  • Silueta
  • Simon Says
  • Simon Says
  • Simon the Spider
  • Simple Addition
  • Simple Polygon
  • Simplicity
  • Single source shortest path, negative weights
  • Single source shortest path, non-negative weights
  • Single source shortest path, time table
  • Six Degrees
  • Sjecista
  • Skener
  • Skocimis
  • Slalom
  • Slatkisi
  • Slikar
  • Slon
  • Smallest Multiple
  • Smart Phone
  • SMS Typing
  • Snapper Chain (Easy)
  • Snapper Chain (Hard)
  • Sneaky Snowninjas
  • S-Nim
  • Social Advertising
  • Soda Surpler
  • Software Bugs
  • Solving for Carrots
  • Sort of Sorting
  • Soylent
  • So you want to be a 2^n-aire?
  • Space Junk
  • Space Probe
  • Spam Filter
  • Spavanac
  • Speaking of Which
  • Speed Limit
  • Speedy Escape
  • Spiderman’s Workout
  • Splat
  • Spock
  • Square Fields (Easy)
  • Square Fields (Hard)
  • Square Peg in a Round Hole
  • Square Pie
  • Squawk Virus
  • Srednji
  • Stack Construction
  • Stacking Cups
  • Stacking Curvy Blocks
  • Stammering Aliens
  • Stand on Zanzibar
  • Statistics
  • Sticky Situation
  • Stirling’s Approximation
  • Stock Prices
  • Stogovi
  • Stol
  • Stretching Streamers
  • String Factoring
  • String Hashing
  • String Matching
  • String Multimatching
  • String Stretching
  • Stuck In A Time Loop
  • Submarines
  • Subway
  • Subway Tree System
  • Succession
  • Sudoku
  • Sudokunique
  • Suffix Array Re-construction
  • Suffix Sorting
  • Šuma
  • Sum Kind of Problem
  • Sum of the Others
  • Sums
  • Sumsets
  • Sunlight
  • Supercomputer
  • Super Mario 169
  • Support Vector Machine
  • Surely You Congest
  • Surveillance
  • Suspension Bridges
  • Svemir
  • Swap Space
  • Sylvester Construction
  • Symmetric Order
  • Synchronizing Lists
  • T9 Spelling
  • Tajna
  • Take Two Stones
  • Target Practice
  • Tarifa
  • Tautology
  • Taxi Cab Scheme
  • Taxing Problem
  • Temperature Confusion
  • Tenis
  • Ternarian Weights
  • Terraces
  • Tetris
  • Texas Summers
  • Text Encryption
  • Text Messaging Outrage
  • Texture Analysis
  • The Amazing Human Cannonball
  • The Backslash Problem
  • The Big Painting
  • The Calculus of Ada
  • The Citrus Intern
  • The Darkness
  • The Dragon of Loowater
  • The Easiest Problem Is This One
  • The End of the World
  • The Escape
  • The Imp
  • The King of the North
  • The King’s Walk
  • The Magical 3
  • The Mailbox Manufacturers Problem
  • The Owl and the Fox
  • The Safe Secret
  • Thesaurus
  • The SetStack Computer
  • The Trip
  • The Uxuhul Voting System
  • The White Rabbit Pocket Watch
  • Three Digits
  • Three Powers
  • Three-State Memory
  • Ticket Draw
  • Ticket Lottery
  • Tide Goes In, Tide Goes Out
  • Tight words
  • Tile Cutting
  • Timebomb
  • Time Travelling Temperatures
  • Timing
  • Toast
  • Toilet Seat
  • ToLower
  • Tomography
  • Tomosynthesis
  • Torn To Pieces
  • Touchscreen Keyboard
  • Tour de France
  • Tourist
  • Tourists
  • Toys
  • Track Smoothing
  • Tractor
  • Train Addiction
  • Train Passengers
  • Train Sorting
  • Translators’ Dinner
  • Trapezoid Walkway
  • Traveling Salesman
  • Travelling Delivery Person
  • Travelling Salesperson 2D
  • Tray Bien
  • Treasure Diving
  • Treasure Hunt
  • Tree Insertion
  • Trending Topic
  • Tri
  • Triangle Ornaments
  • Triangles
  • Triangles
  • Triangle Trilemma
  • Trick or Treat
  • Trik
  • Tri Tiling
  • Troll Hunt
  • Tug of War
  • Turbo
  • Turtle Master
  • Two Knights’ Poem
  • Ultra-QuickSort
  • Un-bear-able Zoo
  • UnDetected
  • (un)Fair Play
  • Unicycle Counting
  • Union-Find
  • Unique Snowflakes
  • Units
  • Unlock Pattern
  • Unusual Darts
  • Vacuumba
  • Vacuum Tubes
  • Vanishing Parentheses
  • Vase Collection
  • Vauvau
  • Veci
  • Vending Machine
  • Verify This, Your Majesty
  • Virtual Friends
  • Virus Replication
  • VisuAlgo Online Quiz
  • VivoParc
  • Vocabulary
  • Volim
  • Volume Amplification
  • Vudu
  • Vuk
  • Walrus Weights
  • Watchdog
  • Watering Grass
  • Weak Vertices
  • Weather Report
  • Weightlifting
  • Welcome to Code Jam (Easy)
  • Welcome to Code Jam (Hard)
  • WERTYU
  • Wet Tiles
  • What Does It Mean?
  • What does the fox say?
  • What’s In It For Me?
  • What’s on the Grille?
  • Wheels
  • Where’s My Internet??
  • Which Base is it Anyway?
  • Whiteboard
  • White Water Rafting
  • Winning Streak
  • Wipe Your Whiteboards
  • Wizard of Odds
  • Wood Cutting
  • Wooden Signs
  • Word Cloud
  • Word Equations
  • WordSpin
  • Working at the Restaurant
  • Worst Weather Ever
  • Xor Maximization
  • Xortris
  • X-ray spectrum
  • Xtreme Driving
  • XYZZY
  • YATP
  • Yet Satisfiability Again!
  • Yin and Yang Stones
  • Yoda
  • Zabava
  • Zagrade
  • Zamka
  • Zapis
  • Zbrka
  • Zgodan
  • Zigzag
  • Zig Zag Nametag
  • Zipf’s Law
  • Zipf’s Song
  • Znanstvenik
  • Zoning
  • UVa Online Judge
    UVa Online Judge is an old online judge with lots of algorithmic problems. See my profile page.

    Solved problems (785)
  • UVa 100: The 3n + 1 problem
  • UVa 101: The Blocks Problem
  • UVa 102: Ecological Bin Packing
  • UVa 103: Stacking Boxes
  • UVa 105: The Skyline Problem
  • UVa 106: Fermat vs. Pythagoras
  • UVa 107: The Cat in the Hat
  • UVa 108: Maximum Sum
  • UVa 111: History Grading
  • UVa 112: Tree Summing
  • UVa 113: Power of Cryptography
  • UVa 116: Unidirectional TSP
  • UVa 118: Mutant Flatworld Explorers
  • UVa 119: Greedy Gift Givers
  • UVa 120: Stacks of Flapjacks
  • UVa 123: Searching Quickly
  • UVa 124: Following Orders
  • UVa 136: Ugly Numbers
  • UVa 138: Street Numbers
  • UVa 140: Bandwidth
  • UVa 146: ID Codes
  • UVa 147: Dollars
  • UVa 151: Power Crisis
  • UVa 152: Tree’s a Crowd
  • UVa 156: Ananagrams
  • UVa 160: Factors and Factorials
  • UVa 161: Traffic Lights
  • UVa 162: Beggar My Neighbour
  • UVa 166: Making Change
  • UVa 167: The Sultan’s Successors
  • UVa 168: Theseus and the Minotaur
  • UVa 173: Network Wars
  • UVa 188: Perfect Hash
  • UVa 191: Intersection
  • UVa 195: Anagram
  • UVa 202: Repeating Decimals
  • UVa 215: Spreadsheet Calculator
  • UVa 256: Quirksome Squares
  • UVa 259: Software Allocation
  • UVa 260: Il Gioco dell’X
  • UVa 263: Number Chains
  • UVa 264: Count on Cantor
  • UVa 271: Simply Syntax
  • UVa 272: TEX Quotes
  • UVa 275: Expanding Fractions
  • UVa 278: Chess
  • UVa 280: Vertex
  • UVa 291: The House Of Santa Claus
  • UVa 294: Divisors
  • UVa 296: Safebreaker
  • UVa 297: Quadtrees
  • UVa 299: Train Swapping
  • UVa 305: Joseph
  • UVa 315: Network
  • UVa 324: Factorial Frequencies
  • UVa 325: Identifying Legal Pascal Real Constants
  • UVa 333: Recognizing Good ISBNs
  • UVa 340: Master-Mind Hints
  • UVa 343: What Base Is This?
  • UVa 344: Roman Digititis
  • UVa 348: Optimal Array Multiplication Sequence
  • UVa 350: Pseudo-Random Numbers
  • UVa 352: The Seasonal War
  • UVa 353: Pesky Palindromes
  • UVa 355: The Bases Are Loaded
  • UVa 357: Let Me Count The Ways
  • UVa 369: Combinations
  • UVa 371: Ackermann Functions
  • UVa 374: Big Mod
  • UVa 382: Perfection
  • UVa 386: Perfect Cubes
  • UVa 389: Basically Speaking
  • UVa 401: Palindromes
  • UVa 406: Prime Cuts
  • UVa 408: Uniform Generator
  • UVa 409: Excuses, Excuses!
  • UVa 412: Pi
  • UVa 414: Machined Surfaces
  • UVa 417: Word Index
  • UVa 422: Word-Search Wonder
  • UVa 423: MPI Maelstrom
  • UVa 424: Integer Inquiry
  • UVa 431: Trial of the Millennium
  • UVa 437: The Tower of Babylon
  • UVa 438: The Circumference of the Circle
  • UVa 439: Knight Moves
  • UVa 440: Eeny Meeny Moo
  • UVa 441: Lotto
  • UVa 442: Matrix Chain Multiplication
  • UVa 443: Humble Numbers
  • UVa 444: Encoder and Decoder
  • UVa 445: Marvelous Mazes
  • UVa 446: Kibbles “n” Bits “n” Bits “n” Bits
  • UVa 454: Anagrams
  • UVa 455: Periodic Strings
  • UVa 457: Linear Cellular Automata
  • UVa 458: The Decoder
  • UVa 459: Graph Connectivity
  • UVa 462: Bridge Hand Evaluator
  • UVa 465: Overflow
  • UVa 466: Mirror, Mirror
  • UVa 469: Wetlands of Florida
  • UVa 471: Magic Numbers
  • UVa 476: Points in Figures: Rectangles
  • UVa 477: Points in Figures: Rectangles and Circles
  • UVa 481: What Goes Up
  • UVa 482: Permutation Arrays
  • UVa 483: Word Scramble
  • UVa 484: The Department of Redundancy Department
  • UVa 485: Pascal’s Triangle of Death
  • UVa 488: Triangle Wave
  • UVa 489: Hangman Judge
  • UVa 490: Rotating Sentences
  • UVa 492: Pig-Latin
  • UVa 494: Kindergarten Counting Game
  • UVa 495: Fibonacci Freeze
  • UVa 496: Simply Subsets
  • UVa 497: Strategic Defense Initiative
  • UVa 498: Polly the Polynomial
  • UVa 499: What’s The Frequency, Kenneth?
  • UVa 507: Jill Rides Again
  • UVa 524: Prime Ring Problem
  • UVa 526: String Distance and Transform Process
  • UVa 530: Binomial Showdown
  • UVa 534: Frogger
  • UVa 537: Artificial Intelligence?
  • UVa 539: The Settlers of Catan
  • UVa 541: Error Correction
  • UVa 543: Goldbach’s Conjecture
  • UVa 551: Nesting a Bunch of Brackets
  • UVa 555: Bridge Hands
  • UVa 556: Amazing
  • UVa 558: Wormholes
  • UVa 562: Dividing coins
  • UVa 563: Crimewave
  • UVa 568: Just the Facts
  • UVa 572: Oil Deposits
  • UVa 573: The Snail
  • UVa 575: Skew Binary
  • UVa 579: Clock Hands
  • UVa 583: Prime Factors
  • UVa 584: Bowling
  • UVa 591: Box of Bricks
  • UVa 594: One Little, Two Little, Three Little Endians
  • UVa 612: DNA Sorting
  • UVa 615: Is It A Tree?
  • UVa 616: Coconuts, Revisited
  • UVa 619: Numerically Speaking
  • UVa 621: Secret Research
  • UVa 622: Grammar Evaluation
  • UVa 623: 500!
  • UVa 624: CD
  • UVa 630: Anagrams (II)
  • UVa 634: Polygon
  • UVa 637: Booklet Printing
  • UVa 640: Self Numbers
  • UVa 642: Word Amalgamation
  • UVa 644: Immediate Decodability
  • UVa 647: Chutes and Ladders
  • UVa 657: The die is cast
  • UVa 661: Blowing Fuses
  • UVa 662: Fast Food
  • UVa 670: The dog task
  • UVa 672: Gangsters
  • UVa 673: Parentheses Balance
  • UVa 674: Coin Change
  • UVa 681: Convex Hull Finding
  • UVa 686: Goldbach’s Conjecture (II)
  • UVa 694: The Collatz Sequence
  • UVa 696: How Many Knights
  • UVa 699: The Falling Leaves
  • UVa 701: The Archeologists’ Dilemma
  • UVa 704: Colour Hash
  • UVa 705: Slash Maze
  • UVa 706: LC-Display
  • UVa 713: Adding Reversed Numbers
  • UVa 714: Copying Books
  • UVa 721: Invitation Cards
  • UVa 725: Division
  • UVa 727: Equation
  • UVa 729: The Hamming Distance Problem
  • UVa 748: Exponentiation
  • UVa 755: 487–3279
  • UVa 763: Fibinary Numbers
  • UVa 776: Monkeys in a Regular Forest
  • UVa 784: Maze Exploration
  • UVa 785: Grid Colouring
  • UVa 793: Network Connections
  • UVa 796: Critical Links
  • UVa 820: Internet Bandwidth
  • UVa 825: Walking on the Safe Side
  • UVa 834: Continued Fractions
  • UVa 836: Largest Submatrix
  • UVa 846: Steps
  • UVa 847: A Multiplication Game
  • UVa 850: Crypt Kicker II
  • UVa 861: Little Bishops
  • UVa 866: Intersecting Line Segments
  • UVa 872: Ordering
  • UVa 884: Factorial Factors
  • UVa 893: Y3K Problem
  • UVa 900: Brick Wall Patterns
  • UVa 902: Password Search
  • UVa 913: Joana and the Odd Numbers
  • UVa 920: Sunny Mountains
  • UVa 929: Number Maze
  • UVa 978: Lemmings Battle!
  • UVa 991: Safe Salutations
  • UVa 1062: Containers
  • UVa 1111: Trash Removal
  • UVa 1121: Subsequence
  • UVa 1124: Celebrity jeopardy
  • UVa 1172: The Bridges of Kolsberg
  • UVa 1203: Argus
  • UVa 1216: The Bug Sensor Problem
  • UVa 1225: Digit Counting
  • UVa 1226: Numerical surprises
  • UVa 1230: MODEX
  • UVa 1232: SKYLINE
  • UVa 1234: RACING
  • UVa 1246: Find Terrorists
  • UVa 1252: Twenty Questions
  • UVa 1291: Dance Dance Revolution
  • UVa 1292: Strategic game
  • UVa 1339: Ancient Cipher
  • UVa 1394: And Then There Was One
  • UVa 1401: Remember the Word
  • UVa 1428: Ping pong
  • UVa 1449: Dominating Patterns
  • UVa 1513: Movie collection
  • UVa 1515: Pool construction
  • UVa 1572: Self-Assembly
  • UVa 1574: Surely You Congest
  • UVa 1575: Factors
  • UVa 1577: Low Power
  • UVa 1581: Pollution Solution
  • UVa 1583: Digit Generator
  • UVa 1584: Circular Sequence
  • UVa 1585: Score
  • UVa 1586: Molar mass
  • UVa 1636: Headshot
  • UVa 1646: Edge Case
  • UVa 1649: Binomial coefficients
  • UVa 1658: Admiral
  • UVa 10002: Center of Masses
  • UVa 10003: Cutting Sticks
  • UVa 10004: Bicoloring
  • UVa 10006: Carmichael Numbers
  • UVa 10007: Count the Trees
  • UVa 10008: What’s Cryptanalysis?
  • UVa 10010: Where’s Waldorf?
  • UVa 10013: Super long sums
  • UVa 10014: Simple calculations
  • UVa 10018: Reverse and Add
  • UVa 10019: Funny Encryption Method
  • UVa 10020: Minimal coverage
  • UVa 10023: Square root
  • UVa 10025: The ? 1 ? 2 ? … ? n = k problem
  • UVa 10026: Shoemaker’s Problem
  • UVa 10028: Demerit Points
  • UVa 10033: Interpreter
  • UVa 10034: Freckles
  • UVa 10035: Primary Arithmetic
  • UVa 10038: Jolly Jumpers
  • UVa 10041: Vito’s Family
  • UVa 10042: Smith Numbers
  • UVa 10049: Self-describing Sequence
  • UVa 10050: Hartals
  • UVa 10054: The Necklace
  • UVa 10055: Hashmat the Brave Warrior
  • UVa 10062: Tell me the frequencies!
  • UVa 10066: The Twin Towers
  • UVa 10070: Leap Year or Not Leap Year and …
  • UVa 10071: Back to High School Physics
  • UVa 10074: Take the Land
  • UVa 10077: The Stern-Brocot Number System
  • UVa 10078: The Art Gallery
  • UVa 10079: Pizza Cutting
  • UVa 10080: Gopher II
  • UVa 10081: Tight Words
  • UVa 10082: WERTYU
  • UVa 10083: Division
  • UVa 10098: Generating Fast
  • UVa 10099: The Tourist Guide
  • UVa 10104: Euclid Problem
  • UVa 10105: Polynomial Coefficients
  • UVa 10106: Product
  • UVa 10107: What is the Median?
  • UVa 10110: Light, more light
  • UVa 10114: Loansome Car Buyer
  • UVa 10115: Automatic Editing
  • UVa 10116: Robot Motion
  • UVa 10127: Ones
  • UVa 10131: Is Bigger Smarter?
  • UVa 10132: File Fragmentation
  • UVa 10137: The Trip
  • UVa 10139: Factovisors
  • UVa 10141: Request for Proposal
  • UVa 10161: Ant on a Chessboard
  • UVa 10162: Last Digit
  • UVa 10165: Stone Game
  • UVa 10168: Summation of Four Primes
  • UVa 10170: The Hotel with Infinite Rooms
  • UVa 10176: Ocean Deep! – Make it shallow!!
  • UVa 10179: Irreducable Basic Fractions
  • UVa 10181: 15-Puzzle Problem
  • UVa 10183: How Many Fibs?
  • UVa 10188: Automated Judge Script
  • UVa 10189: Minesweeper
  • UVa 10191: Longest Nap
  • UVa 10192: Vacation
  • UVa 10198: Counting
  • UVa 10203: Snow Clearing
  • UVa 10205: Stack ’em Up
  • UVa 10209: Is This Integration ?
  • UVa 10219: Find the ways !
  • UVa 10220: I Love Big Numbers !
  • UVa 10222: Decode the Mad man
  • UVa 10226: Hardwood Species
  • UVa 10229: Modular Fibonacci
  • UVa 10235: Simply Emirp
  • UVa 10245: The Closest Pair Problem
  • UVa 10249: The Grand Dinner
  • UVa 10252: Common Permutation
  • UVa 10258: Contest Scoreboard
  • UVa 10260: Soundex
  • UVa 10263: Railway
  • UVa 10267: Graphical Editor
  • UVa 10268: 498-bis
  • UVa 10279: Mine Sweeper
  • UVa 10281: Average Speed
  • UVa 10282: Babelfish
  • UVa 10284: Chessboard in FEN
  • UVa 10285: Longest Run on a Snowboard
  • UVa 10295: Hay Points
  • UVa 10298: Power Strings
  • UVa 10299: Relatives
  • UVa 10300: Ecological Premium
  • UVa 10302: Summation of Polynomials
  • UVa 10303: How Many Trees?
  • UVa 10304: Optimal Binary Search Tree
  • UVa 10305: Ordering Tasks
  • UVa 10306: e-Coins
  • UVa 10310: Dog and Gopher
  • UVa 10316: Airline Hub
  • UVa 10319: Manhattan
  • UVa 10323: Factorial! You Must be Kidding!!!
  • UVa 10324: Zeros and Ones
  • UVa 10327: Flip Sort
  • UVa 10330: Power Transmission
  • UVa 10334: Ray Through Glasses
  • UVa 10336: Rank the Languages
  • UVa 10338: Mischievous Children
  • UVa 10340: All in All
  • UVa 10341: Solve It
  • UVa 10346: Peter’s Smokes
  • UVa 10347: Medians
  • UVa 10359: Tiling
  • UVa 10361: Automatic Poetry
  • UVa 10363: Tic Tac Toe
  • UVa 10367: Equations
  • UVa 10370: Above Average
  • UVa 10374: Election
  • UVa 10375: Choose and divide
  • UVa 10377: Maze Traversal
  • UVa 10387: Billiard
  • UVa 10392: Factoring Large Numbers
  • UVa 10394: Twin Primes
  • UVa 10397: Connect the Campus
  • UVa 10401: Injured Queen Problem
  • UVa 10404: Bachet’s Game
  • UVa 10405: Longest Common Subsequence
  • UVa 10408: Farey sequences
  • UVa 10409: Die Game
  • UVa 10420: List of Conquests
  • UVa 10422: Knights in FEN
  • UVa 10424: Love Calculator
  • UVa 10427: Naughty Sleepy Boys
  • UVa 10432: Polygon Inside A Circle
  • UVa 10450: World Cup Noise
  • UVa 10453: Make Palindrome
  • UVa 10464: Big Big Real Numbers
  • UVa 10465: Homer Simpson
  • UVa 10469: To Carry or not to Carry
  • UVa 10473: Simple Base Conversion
  • UVa 10474: Where is the Marble?
  • UVa 10480: Sabotage
  • UVa 10487: Closest Sums
  • UVa 10490: Mr. Azad and his Son!!!!!
  • UVa 10494: If We Were a Child Again
  • UVa 10499: The Land of Justice
  • UVa 10511: Councilling
  • UVa 10515: Powers Et Al.
  • UVa 10523: Very Easy !!!
  • UVa 10530: Guessing Game
  • UVa 10533: Digit Primes
  • UVa 10534: Wavio Sequence
  • UVa 10539: Almost Prime Numbers
  • UVa 10544: Numbering the Paths
  • UVa 10550: Combination Lock
  • UVa 10551: Basic Remains
  • UVa 10578: The Game of 31
  • UVa 10579: Fibonacci Numbers
  • UVa 10583: Ubiquitous Religions
  • UVa 10589: Area
  • UVa 10591: Happy Number
  • UVa 10592: Freedom Fighter
  • UVa 10608: Friends
  • UVa 10611: The Playboy Chimp
  • UVa 10621: Jack and Jill
  • UVa 10622: Perfect P-th Powers
  • UVa 10626: Buying Coke
  • UVa 10633: Rare Easy Problem
  • UVa 10635: Prince and Princess
  • UVa 10646: What is the Card?
  • UVa 10650: Determinate Prime
  • UVa 10651: Pebble Solitaire
  • UVa 10656: Maximum Sum (II)
  • UVa 10679: I Love Strings!!
  • UVa 10680: LCM
  • UVa 10681: Teobaldo’s Trip
  • UVa 10683: The decadary watch
  • UVa 10684: The jackpot
  • UVa 10689: Yet another Number Sequence
  • UVa 10696: f91
  • UVa 10699: Count the factors
  • UVa 10700: Camel trading
  • UVa 10703: Free spots
  • UVa 10714: Ants
  • UVa 10718: Bit Mask
  • UVa 10739: String to Palindrome
  • UVa 10755: Garbage Heap
  • UVa 10763: Foreign Exchange
  • UVa 10776: Determine The Combination
  • UVa 10783: Odd Sum
  • UVa 10784: Diagonal
  • UVa 10789: Prime Frequency
  • UVa 10790: How Many Points of Intersection?
  • UVa 10800: Not That Kind of Graph
  • UVa 10803: Thunder Mountain
  • UVa 10806: Dijkstra, Dijkstra.
  • UVa 10812: Beat the Spread!
  • UVa 10814: Simplifying Fractions
  • UVa 10815: Andy’s First Dictionary
  • UVa 10820: Send a Table
  • UVa 10851: 2D Hieroglyphs decoder
  • UVa 10856: Recover Factorial
  • UVa 10862: Connect the Cable Wires
  • UVa 10870: Recurrences
  • UVa 10878: Decode the tape
  • UVa 10879: Code Refactoring
  • UVa 10891: Game of Sum
  • UVa 10901: Ferry Loading III
  • UVa 10905: Children’s Game
  • UVa 10911: Forming Quiz Teams
  • UVa 10919: Prerequisites?
  • UVa 10921: Find the Telephone
  • UVa 10922: 2 the 9s
  • UVa 10924: Prime Words
  • UVa 10925: Krakovia
  • UVa 10929: You can say 11
  • UVa 10931: Parity
  • UVa 10938: Flea circus
  • UVa 10943: How do you add?
  • UVa 10945: Mother bear
  • UVa 10948: The primary problem
  • UVa 10954: Add All
  • UVa 10963: The Swallowing Ground
  • UVa 10970: Big Chocolate
  • UVa 10986: Sending email
  • UVa 10994: Simple Addition
  • UVa 11000: Bee
  • UVa 11028: Sum of Product
  • UVa 11030: Predator II
  • UVa 11036: Eventually Periodic Sequence
  • UVa 11044: Searching for Nessy
  • UVa 11045: My T-shirt suits me
  • UVa 11057: Exact Sum
  • UVa 11059: Maximum Product
  • UVa 11060: Beverages
  • UVa 11062: Andy’s Second Dictionary
  • UVa 11065: A Gentlemen’s Agreement
  • UVa 11069: A Graph Problem
  • UVa 11074: Draw Grid
  • UVa 11078: Open Credit System
  • UVa 11080: Place the Guards
  • UVa 11094: Continents
  • UVa 11107: Life Forms
  • UVa 11110: Equidivisions
  • UVa 11111: Generalized Matrioshkas
  • UVa 11136: Hoax or what
  • UVa 11137: Ingenuous Cubrency
  • UVa 11138: Nuts and Bolts
  • UVa 11151: Longest Palindrome
  • UVa 11159: Factors and Multiples
  • UVa 11161: Help My Brother (II)
  • UVa 11163: Jaguar King
  • UVa 11171: SMS
  • UVa 11172: Relational Operator
  • UVa 11173: Grey Codes
  • UVa 11183: Teen Girl Squad
  • UVa 11185: Ternary
  • UVa 11192: Group Reverse
  • UVa 11195: Another n-Queen Problem
  • UVa 11203: Can you decide it for ME?
  • UVa 11218: KTV
  • UVa 11219: How old are you?
  • UVa 11221: Magic square palindromes.
  • UVa 11222: Only I did it!
  • UVa 11235: Frequent values
  • UVa 11239: Open Source
  • UVa 11242: Tour de France
  • UVa 11258: String Partition
  • UVa 11278: One-Handed Typist
  • UVa 11279: Keyboard Comparison
  • UVa 11286: Conformity
  • UVa 11287: Pseudoprime Numbers
  • UVa 11292: Dragon of Loowater
  • UVa 11294: Wedding
  • UVa 11296: Counting Solutions to an Integral Equation
  • UVa 11309: Counting Chaos
  • UVa 11310: Delivery Debacle
  • UVa 11321: Sort! Sort!! and Sort!!!
  • UVa 11324: The Largest Clique
  • UVa 11332: Summing Digits
  • UVa 11340: Newspaper
  • UVa 11342: Three-square
  • UVa 11344: The Huge One
  • UVa 11345: Rectangles
  • UVa 11347: Multifactorials
  • UVa 11349: Symmetric Matrix
  • UVa 11350: Stern-Brocot Tree
  • UVa 11351: Last Man Standing
  • UVa 11356: Dates
  • UVa 11360: Have Fun with Matrices
  • UVa 11362: Phone List
  • UVa 11364: Parking
  • UVa 11368: Nested Dolls
  • UVa 11369: Shopaholic
  • UVa 11388: GCD LCM
  • UVa 11401: Triangle Counting
  • UVa 11405: Can U Win?
  • UVa 11414: Dream
  • UVa 11417: GCD
  • UVa 11418: Clever Naming Patterns
  • UVa 11419: SAM I AM
  • UVa 11424: GCD – Extreme (I)
  • UVa 11426: GCD – Extreme (II)
  • UVa 11428: Cubes
  • UVa 11448: Who said crisis?
  • UVa 11455: Behold my quadrangle
  • UVa 11456: Trainsorting
  • UVa 11459: Snakes and Ladders
  • UVa 11461: Square Numbers
  • UVa 11462: Age Sort
  • UVa 11463: Commandos
  • UVa 11466: Largest Prime Divisor
  • UVa 11470: Square Sums
  • UVa 11479: Is this the easiest problem?
  • UVa 11480: Jimmy’s Balls
  • UVa 11483: Code Creator
  • UVa 11494: Queen
  • UVa 11495: Bubbles and Buckets
  • UVa 11498: Division of Nlogonia
  • UVa 11503: Virtual Friends
  • UVa 11504: Dominos
  • UVa 11514: Batman
  • UVa 11517: Exact Change
  • UVa 11518: Dominos 2
  • UVa 11525: Permutation
  • UVa 11530: SMS Typing
  • UVa 11536: Smallest Sub-Array
  • UVa 11541: Decoding
  • UVa 11547: Automatic Answer
  • UVa 11549: Calculator Conundrum
  • UVa 11554: Hapless Hedonism
  • UVa 11555: Aspen Avenue
  • UVa 11556: Best Compression Ever
  • UVa 11559: Event Planning
  • UVa 11561: Getting Gold
  • UVa 11565: Simple Equations
  • UVa 11569: Lovely Hint
  • UVa 11573: Ocean Currents
  • UVa 11576: Scrolling Sign
  • UVa 11577: Letter Frequency
  • UVa 11581: Grid Successors
  • UVa 11584: Partitioning by Palindromes
  • UVa 11586: Train Tracks
  • UVa 11594: All Pairs Maximum Flow
  • UVa 11597: Spanning Subtree
  • UVa 11600: Masud Rana
  • UVa 11605: Lights inside a 3d Grid
  • UVa 11608: No Problem
  • UVa 11609: Teams
  • UVa 11610: Reverse Prime
  • UVa 11614: Etruscan Warriors Never Play Chess
  • UVa 11616: Roman Numerals
  • UVa 11621: Small Factors
  • UVa 11629: Ballot evaluation
  • UVa 11631: Dark roads
  • UVa 11634: Generate random numbers
  • UVa 11636: Hello World!
  • UVa 11650: Mirror Clock
  • UVa 11661: Burger Time?
  • UVa 11677: Alarm Clock
  • UVa 11679: Sub-prime
  • UVa 11687: Digits
  • UVa 11689: Soda Surpler
  • UVa 11690: Money Matters
  • UVa 11692: Rain Fall
  • UVa 11693: Speedy Escape
  • UVa 11694: Gokigen Naname
  • UVa 11697: Playfair Cipher
  • UVa 11703: sqrt log sin
  • UVa 11713: Abstract Names
  • UVa 11715: Car
  • UVa 11716: Digital Fortress
  • UVa 11723: Numbering Roads
  • UVa 11727: Cost Cutting
  • UVa 11728: Alternate Task
  • UVa 11729: Commando War
  • UVa 11734: Big Number of Teams will Solve This
  • UVa 11743: Credit Check
  • UVa 11744: Parallel Carry Adder
  • UVa 11749: Poor Trade Advisor
  • UVa 11764: Jumping Mario
  • UVa 11777: Automate the Grades
  • UVa 11782: Optimal Cut
  • UVa 11786: Global Raining at Bididibus
  • UVa 11787: Numeral Hieroglyphs
  • UVa 11790: Murcia’s Skyline
  • UVa 11797: Drutojan Express
  • UVa 11799: Horror Dash
  • UVa 11804: Argentina
  • UVa 11805: Bafana Bafana
  • UVa 11821: High-Precision Number
  • UVa 11824: A Minimum Land Price
  • UVa 11827: Maximum GCD
  • UVa 11830: Contract Revision
  • UVa 11831: Sticker Collector Robot
  • UVa 11838: Come and Go
  • UVa 11839: Optical Reader
  • UVa 11849: CD
  • UVa 11850: Alaska
  • UVa 11854: Egypt
  • UVa 11858: Frosh Week
  • UVa 11860: Document Analyzer
  • UVa 11875: Brick Game
  • UVa 11876: N + NOD (N)
  • UVa 11877: The Coco-Cola Store
  • UVa 11878: Homework Checker
  • UVa 11879: Multiple of 17
  • UVa 11889: Benefit
  • UVa 11900: Boiled Eggs
  • UVa 11909: Soya Milk
  • UVa 11917: Do Your Own Homework
  • UVa 11926: Multitasking
  • UVa 11933: Splitting Numbers
  • UVa 11934: Magic Formula
  • UVa 11936: The Lazy Lumberjacks
  • UVa 11942: Lumberjack Sequencing
  • UVa 11946: Code Number
  • UVa 11953: Battleships
  • UVa 11955: Binomial Theorem
  • UVa 11956: Brainfuck
  • UVa 11960: Divisor Game
  • UVa 11965: Extra Spaces
  • UVa 11984: A Change in Thermal Unit
  • UVa 11987: Almost Union-Find
  • UVa 11988: Broken Keyboard (a.k.a. Beiju Text)
  • UVa 11991: Easy Problem from Rujia Liu?
  • UVa 11995: I Can Guess the Data Structure!
  • UVa 12015: Google is Feeling Lucky
  • UVa 12019: Doom’s Day Algorithm
  • UVa 12027: Very Big Perfect Squares
  • UVa 12043: Divisors
  • UVa 12049: Just Prune The List
  • UVa 12068: Harmonic Mean
  • UVa 12083: Guardian of Decency
  • UVa 12085: Mobile Casanova
  • UVa 12086: Potentiometers
  • UVa 12090: Counting Zeroes
  • UVa 12095: Sudoku
  • UVa 12097: Pie
  • UVa 12124: Assemble
  • UVa 12125: March of the Penguins
  • UVa 12149: Feynman
  • UVa 12157: Tariff Plan
  • UVa 12160: Unlock the Lock
  • UVa 12166: Equilibrium Mobile
  • UVa 12167: Proving Equivalences
  • UVa 12168: Cat vs. Dog
  • UVa 12169: Disgruntled Judge
  • UVa 12173: White Water Rafting
  • UVa 12187: Brothers
  • UVa 12205: Happy Telephones
  • UVa 12206: Stammering Aliens
  • UVa 12208: How Many Ones Needed?
  • UVa 12239: Bingo!
  • UVa 12243: Flowers Flourish from France
  • UVa 12247: Jollo
  • UVa 12250: Language Detection
  • UVa 12269: Lawn mower
  • UVa 12279: Emoogle Balance
  • UVa 12280: A Digital Satire of Digital Age
  • UVa 12289: One-Two-Three
  • UVa 12337: Bob’s Beautiful Balls
  • UVa 12342: Tax Calculator
  • UVa 12356: Army Buddies
  • UVa 12363: Hedge Mazes
  • UVa 12366: King’s Poker
  • UVa 12372: Packing for Holiday
  • UVa 12379: Central Post Office
  • UVa 12390: Distributing Ballot Boxes
  • UVa 12391: Game, Set and Match
  • UVa 12394: Peer Review
  • UVa 12395: Regular Convex Polygon
  • UVa 12403: Save Setu
  • UVa 12405: Scarecrow
  • UVa 12416: Excessive Space Remover
  • UVa 12439: February 29
  • UVa 12442: Forwarding Emails
  • UVa 12455: Bars
  • UVa 12459: Bees’ ancestors
  • UVa 12463: Little Nephew
  • UVa 12468: Zapping
  • UVa 12470: Tribonacci
  • UVa 12478: Hardest Problem Ever (Easy)
  • UVa 12502: Three Families
  • UVa 12503: Robot Instructions
  • UVa 12504: Updating a Dictionary
  • UVa 12505: Searching in sqrt(n)
  • UVa 12515: Movie Police
  • UVa 12516: Cinema-cola
  • UVa 12524: Arranging Heaps
  • UVa 12526: Cellphone Typing
  • UVa 12527: Different Digits
  • UVa 12531: Hours and Minutes
  • UVa 12532: Interval Product
  • UVa 12541: Birthdates
  • UVa 12542: Prime Substring
  • UVa 12543: Longest Word
  • UVa 12554: A Special “Happy Birthday” Song!!!
  • UVa 12555: Baby Me
  • UVa 12564: King of Fighters explained
  • UVa 12573: Sohel Sir’s Assignment
  • UVa 12575: Sin Cos Problem
  • UVa 12577: Hajj-e-Akbar
  • UVa 12578: 10:6:2
  • UVa 12580: Yell Classico
  • UVa 12582: Wedding of Sultan
  • UVa 12583: Memory Overflow
  • UVa 12585: Poker End Games
  • UVa 12586: Overlapping Characters
  • UVa 12592: Slogan Learning of Princess
  • UVa 12602: Nice Licence Plates
  • UVa 12608: Garbage Collection
  • UVa 12611: Beautiful Flag
  • UVa 12614: Earn For Future
  • UVa 12619: Just Make A Wish
  • UVa 12621: On a Diet
  • UVa 12626: I ❤ Pizza
  • UVa 12627: Erratic Expansion
  • UVa 12630: Equilateral Triangle in a Triangle Grid
  • UVa 12640: Largest Sum Game
  • UVa 12643: Tennis Rounds
  • UVa 12646: Zero or One
  • UVa 12648: Boss
  • UVa 12650: Dangerous Dive
  • UVa 12651: Triangles
  • UVa 12653: Buses
  • UVa 12662: Good Teacher
  • UVa 12667: Last Blood
  • UVa 12671: Disjoint water supply
  • UVa 12672: Eleven
  • UVa 12673: Football
  • UVa 12677: Join two kingdoms
  • UVa 12694: Meeting Room Arrangement
  • UVa 12696: Cabin Baggage
  • UVa 12700: Banglawash
  • UVa 12704: Little Masters
  • UVa 12708: GCD The Largest
  • UVa 12808: Banning Balconing
  • UVa 12822: Extraordinarily large LED
  • UVa 12908: The book thief
  • Codeforces
    Codeforces probably has the most active competitive programming community. I occasionally participate in their contests. See my profile page.

    Solved problems (375)
  • A – 2Char
  • A – A + B
  • A – ABBA
  • A – Achromatic Number
  • A – Alice and Bob
  • A – Amusing Joke
  • A – Aqueduct Construction
  • A – Army buddies
  • A – Arrival of the General
  • A – Average Numbers
  • A – Average distance
  • A – Bear and Poker
  • A – Beautiful Matrix
  • A – Beautiful Year
  • A – Boy or Girl
  • A – Boys and Girls
  • A – Brackets Subsequences
  • A – Buggy Sorting
  • A – Cards with Numbers
  • A – Chat room
  • A – Chewbaсca and Number
  • A – Chinese Girls’ Amusement
  • A – Chores
  • A – Connect and Disconnect
  • A – Crypto Columns
  • A – DZY Loves Physics
  • A – Die Roll
  • A – Dividing Orange
  • A – Domino piling
  • A – Double Cola
  • A – Duff and Weight Lifting
  • A – Epic Game
  • A – Expecting Trouble
  • A – Face Detection
  • A – Fancy Fence
  • A – Far Relative’s Birthday Cake
  • A – Fight the Monster
  • A – Find Amir
  • A – Football
  • A – Game
  • A – Gene Shuffle
  • A – Gravity Flip
  • A – HQ9+
  • A – Helpful Maths
  • A – Hexadecimal’s theorem
  • A – Hexagonal Numbers
  • A – Hexagonal numbers
  • A – Holidays
  • A – I_love_\%username\%
  • A – Inna and Choose Options
  • A – Insomnia cure
  • A – Is your horseshoe on the other hoof?
  • A – Lala Land and Apple Trees
  • A – Lineland Mail
  • A – Lucky Division
  • A – Lucky Permutation Triple
  • A – Malek Dance Club
  • A – Manhattan
  • A – Mashmokh and Numbers
  • A – Mishka and Game
  • A – Mysterious numbers – 1
  • A – Mysterious strings
  • A – Nearly Lucky Number
  • A – Next Round
  • A – Parallelepiped
  • A – Password Check
  • A – Pegman
  • A – Pentagonal numbers
  • A – Perfect Pair
  • A – Peter and Snow Blower
  • A – Petr and Book
  • A – Petya and Strings
  • A – Phone Code
  • A – Points on Line
  • A – Poster
  • A – Pouring Rain
  • A – Presents
  • A – Rational Resistance
  • A – Rebus
  • A – Recycling Bottles
  • A – Reorder the Array
  • A – Rock-Paper-Scissors
  • A – Sereja and Contest
  • A – Shooshuns and Sequence
  • A – Slightly Decreasing Permutations
  • A – Slime Combining
  • A – Sonya and Queries
  • A – Sorting Railway Cars
  • A – Spyke Talks
  • A – Strange Addition
  • A – String Task
  • A – Super Agent
  • A – Team
  • A – The Closest Pair
  • A – The Great Game
  • A – The Wall
  • A – Theatre Square
  • A – Thor
  • A – Tram
  • A – Triangle
  • A – Tricky Sum
  • A – Twins
  • A – Two Bags of Potatoes
  • A – Two Bases
  • A – Ultra-Fast Mathematician
  • A – Vacations
  • A – Vasya and Petya’s Game
  • A – Watchmen
  • A – Watermelon
  • A – Way Too Long Words
  • A – Where do I Turn?
  • A – Xenia and Divisors
  • A – Xor-tree
  • A – Young Physicist
  • A – cAPS lOCK
  • B – A + Reverse B
  • B – Alternating Current
  • B – Amr and The Large Array
  • B – Ant Man
  • B – Anton and Lines
  • B – Approximating a Constant Range
  • B – Ball Stacking
  • B – Bear and Blocks
  • B – Beloved Sons
  • B – Berland National Library
  • B – Binary notation
  • B – Bus Pass
  • B – Coat of Anticubism
  • B – Collatz Conjecture
  • B – Combination
  • B – Command Line Arguments
  • B – Continued Fractions
  • B – Correct Solution?
  • B – Cosmic Tables
  • B – Decorations
  • B – Duff in Beach
  • B – Easy Tape Programming
  • B – Far Relative’s Problem
  • B – Fix a Tree
  • B – Fox and Cross
  • B – Game of Robots
  • B – Gnikool Ssalg
  • B – Greg and Graph
  • B – Guess the Permutation
  • B – Han Solo and Lazer Gun
  • B – Image Preview
  • B – International Olympiad
  • B – Invariance of Tree
  • B – Jury Size
  • B – Lazy Student
  • B – Looksery Party
  • B – Mashmokh and ACM
  • B – Minimum number of steps
  • B – Mishka and trip
  • B – Mountain Biking
  • B – Multi-core Processor
  • B – Mushroom Scientists
  • B – Mysterious Language
  • B – Network Configuration
  • B – Opposites Attract
  • B – Password
  • B – Peragrams
  • B – Physics Practical
  • B – Playing with Permutations
  • B – Present from Lena
  • B – President’s Office
  • B – Pseudorandom Sequence Period
  • B – QR code
  • B – Queries on a String
  • B – Replacing Digits
  • B – Robin Hood
  • B – Running Student
  • B – Skills
  • B – Star
  • B – Strip
  • B – Taxi
  • B – Top 2000
  • B – Triskaidekaphobia
  • B – Unary
  • B – Undoubtedly Lucky Numbers
  • B – Vasya’s Calendar
  • B – Working out
  • B – Xenia and Ringroad
  • B – Xenia and Spies
  • B1 – Permutations
  • B2 – Permutations
  • C – A Piece of Cake
  • C – Alice, Bob and Chocolate
  • C – Amr and Chemistry
  • C – Bus
  • C – Candys Candy
  • C – Cd and pwd commands
  • C – Chris and Road
  • C – Ciel the Commander
  • C – Cinema
  • C – Codeword
  • C – Conversation Log
  • C – Cutting Banknotes
  • C – Decimal sum
  • C – Duff in the Army
  • C – EKG Sequence
  • C – Famil Door and Brackets
  • C – Fruits
  • C – Geometric Progression
  • C – Given Length and Sum of Digits…
  • C – Graph Coloring
  • C – Graph Reconstruction
  • C – Hexadecimal’s Numbers
  • C – Ice cream coloring
  • C – Ivan and Powers of Two
  • C – Kicker
  • C – LCM
  • C – Magnum Opus
  • C – Median
  • C – Nearest vectors
  • C – Necklace
  • C – Network Mask
  • C – Not Wool Sequences
  • C – Number of Ways
  • C – Optimal Sum
  • C – Pattern
  • C – Prefix Product Sequence
  • C – Propagating tree
  • C – Reberland Linguistics
  • C – Second price auction
  • C – Spy Syndrome 2
  • C – Table Compression
  • C – Team
  • C – Text Editor
  • C – Text Encryption
  • C – The Game Of Parity
  • C – The Twin Tower
  • C – The Two Routes
  • C – The World is a Theatre
  • C – Turing Tape
  • C – Vacuum Tubes
  • C – WTF?
  • C – Watto and Mechanism
  • D – Antimatter
  • D – Asterisks
  • D – Babaei and Birthday Cake
  • D – Big Data
  • D – Broken checker
  • D – Bubble Sort
  • D – Bubble Sort Graph
  • D – Calendar Reform
  • D – Chicken Joggers
  • D – Chloe and pleasant prizes
  • D – Collatz
  • D – Common Divisors
  • D – Diccionario Portunol
  • D – Dice Password Security
  • D – Drum Decorator
  • D – Everyone out of the Pool
  • D – Expected diameter of a tree
  • D – Exponentiation
  • D – Guess Your Way Out! II
  • D – Haar Features
  • D – Hamiltonian Spanning Tree
  • D – How many trees?
  • D – Hydra
  • D – Ice Sculptures
  • D – Jeff and Removing Periods
  • D – Matrix Multiplication
  • D – Mishka and Interesting sum
  • D – One-Dimensional Battle Ships
  • D – Orange
  • D – Palindrome Degree
  • D – Parallel Programming
  • D – Phone Home
  • D – Powerful array
  • D – R2D2 and Droid Army
  • D – Remove digits
  • D – Ring Road 2
  • D – Stacking Cubes
  • D – Subway
  • D – Tree and Queries
  • D – Tricky Function
  • D – Turtles
  • D – World Tour
  • D1 – Constrained Tree
  • D1 – Magic Powder – 1
  • D2 – Magic Powder – 2
  • E – A Simple Task
  • E – Bits of merry old England
  • E – Build String
  • E – Chocolate Bar
  • E – Ciel and Gondolas
  • E – Compatible Numbers
  • E – Correct Bracket Sequence Editor
  • E – DZY Loves Planting
  • E – Darth Vader and Tree
  • E – Decoding Genome
  • E – Disconnected Graph
  • E – Dome
  • E – E-mail Addresses
  • E – Electrical Pollution
  • E – Elvis Presley
  • E – Exposition
  • E – Famil Door and Roads
  • E – HQ9+
  • E – HQ9+
  • E – Lingo
  • E – Lomsat gelral
  • E – Polly Nomials
  • E – President and Roads
  • E – Tetrahedron
  • E – The Child and Binary Tree
  • E – The Road to Berland is Paved With Good Intentions
  • E – Tribonacci numbers
  • E – Wooden Fence
  • E – Xenia and Tree
  • F – Bank Queue
  • F – Factorial zeros
  • F – File Retrieval
  • F – Intergalactic Mortgage
  • F – Mausoleum
  • F – Maze Recognition
  • F – Permutations with Monotonic Segments
  • F – Prime factorization
  • F – Pushing Boxes
  • F – Restore a Number
  • F – Splitting the Loot
  • F – To Bet or Not To Bet
  • F – ucyhf
  • F1 – Scaygerboss
  • F2 – Scaygerboss
  • G – CAPS LOCK ON
  • G – Cipher Message 3
  • G – Drink Responsibly
  • G – Forest Highway
  • G – Happy Line
  • G – PL/Cool
  • G – Pachinko
  • G – Persistent Queue
  • G – Snooker
  • G – Squadtrees
  • G – The Problem to Slow Down You
  • G1 – Inversions problem
  • G2 – Inversions problem
  • H – A + B Strikes Back
  • H – Balanced brackets
  • H – Degenerate Matrix
  • H – Double Trouble
  • H – FreeCell
  • H – Hedge Mazes
  • H – Sunlight
  • H – This Takes the Cake
  • I – Array sorting
  • I – Crazy Wall
  • I – Domino tiling
  • I – Flag Quiz
  • I – Graph of Inversions
  • I – In Braille
  • I – Keylogger
  • I – Nimionese
  • I – Ranking
  • I – Wally World
  • J – Brackets
  • J – Cigarettes
  • J – Common Permutation
  • J – Jelly Raid
  • J – Jimi Hendrix
  • J – Jupiter Attacks!
  • J – Saving the Universe
  • J – Stock
  • J – Wrong Answer
  • K – Chessboard in FEN
  • K – Kings Poker
  • K – Korn
  • K – Who is who’s boss?
  • L – 01
  • L – Crossed ladders
  • L – Young Diagrams
  • M – Milestone Counter
  • 19 Comments

    1. Xiao_Mu Xiao_Mu

      Fantastic!

      Could you please tell me how to make an automatically updated list like yours?

      Best regards!

    2. S.C S.C

      That’s a brilliant page.
      I’m also interested in the list above.Can you tell me how it was formed?
      Thanks

    3. Lam Gia Thuan Lam Gia Thuan

      It would be great if you can create a blog of hints for problems that you have solved.

    4. michael michael

      hey man i’ve been attacking the prolbem “exponial” on kattis for 5 hours now and was finally able to solve all the given testcases. however, i still failed some blackbox tests apparently. i’ve looked all over the internet but was unable to find anything. test cases are extremely hard to construct on my own so could you give me some test cases (or even better the source code for that problem)?
      if you can run these cases on your code and tell me the answers that’d be great:
      56 741
      13 45
      167 569
      thanks a lot!!!

    5. Bhishmaraj Selvamani Bhishmaraj Selvamani

      How do you keep track of your solved problems . Do you manually add the solved problems to your blog ?

        • Noah Hunt-Isaak Noah Hunt-Isaak

          How do you do this? I think the idea of writing “scripts” to automate tasks such as this is super cool but I don’t really have any idea how to get started. Do you use something like python? Any tips about how I could get started learning how to do this would be much appreciated.

    6. Bryant Bryant

      Is it possible to get your code to a specific problem?

    7. berrytchaks berrytchaks

      Hi,

      I have spent days on the codes problem of kattis but still my test cases are not passing.
      Please can you provide me with some test cases or links where I could generate some test cases.

      Thanks

    8. unknown unknown

      for problem F posterize, I understand you divide like this DP(i,j) = min_k {DP(k, j-1) + cost(k+1, i)} where i = # red values, using j = #allowed values

      Now to compute the cost function cost(i,j) you have 4 variables: i starting index, j last index, k sum of values and x variable that minimize the sum, how can you compute the cost function without using 4 for loops? I have seen some people doing it only on 3 for loops, but I don’t understand why it works.

      Thanks in advance.

    9. Hi,
      How can I prove the solution for “exponial”?

    10. Julian Julian

      Hello

      How can you solve the problem in java of the book thief?

      Because I used the quadratic equation to solve it and then take the formula of the summation, when this sum is 1 + 2 + 3 + 4 + 5

      If you have a better solution, I would appreciate it if you would share it with me.

      Thank you

    11. Saurabh Saurabh

      Which is best site according to you ?

    12. Akib Akib

      Can you explain how you solved UVa 861? Thanks

    13. Bt3gus Bt3gus

      My python program for 0-1 sequences of kattis works properly, but I am still getting Time Limit Exceeded… Is python code slow or Should use special formula to solve this problem??

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