As of 2018-02-12, CodeEval has ceased operations. This (unofficial) repository mirrors* the problem statements for all 239‡ interactive challenges that once lived on the platform.
* A couple of problem statements are missing animated GIFs which I don't have a backup of. They were supplementary and are not required to solve the challenges in question.
‡ Technically, there were 240 challenges on the platform. Challenge #127 ("Code Plagiarism") wasn't an interactive/graded challenge; thus no points were awarded for it by the online evaluation system.
| CID | Name | Synopsis |
|---|---|---|
| 152 | Age Distribution | Print out where the person is |
| 082 | Armstrong Numbers | Determine if a number is an armstrong number |
| 083 | Beautiful Strings | Facebook Hacker Cup 2013 problem |
| 163 | Big Digits | Print out magnified digits using pseudographics |
| 019 | Bit Positions | Bits in position x,y are same or different |
| 222 | Black Card | Find the winner |
| 099 | Calculate Distance | Calculate a distance between two points |
| 093 | Capitalize Words | Capitalize words in a sentence |
| 211 | Chardonnay or Cabernet | Guess a wine name |
| 205 | Clean Up the Words | Print the words separated by spaces |
| 192 | Compare Points | Given two (x, y) points A and B, determine which cardinal direction B is from A |
| 128 | Compressed Sequence | Write a program that compresses a sequence of numbers |
| 140 | Data Recovery | Reconstruct a sentence using hints |
| 166 | Delta Time | Find the time difference |
| 183 | Details | Determine how many cells will be shifted detail |
| 100 | Even Numbers | Determine if a number is even or not |
| 022 | Fibonacci Series | Print out the nth fibonacci number |
| 026 | File Size | Print the file size in bytes |
| 097 | Find a Writer | Find a famous writer in a string |
| 208 | Find the Highest Score | Find the highest rate in the table |
| 001 | Fizz Buzz | A simple game involving divisibility tests |
| 230 | Football | Find countries that are football fans |
| 039 | Happy Numbers | Determine if a number is a happy number or not |
| 067 | Hex to Decimal | Convert a hex number to it's decimal equivalent |
| 122 | Hidden Digits | Try to look behind the scenes |
| 102 | JSON Menu IDs | Calculate IDs in JSON menu |
| 149 | Juggling With Zeros | Convert a zero-based number into integer |
| 180 | Knight Moves | Find positions for the next move of the knight |
| 147 | Lettercase Percentage Ratio | Find the percentage ratio |
| 111 | Longest Word | Get the longest word in a sentence |
| 020 | Lowercase | Lowercase text |
| 103 | Lowest Unique Number | Find the lowest unique number in a set |
| 178 | Matrix Rotation | Rotate a 2D matrix 90 degrees clockwise |
| 186 | Max Range Sum | Determine max sum at the range |
| 240 | Mersenne Prime | Find all Mersenne numbers smaller than n |
| 189 | Minimum Distance | Find a point with the smallest sum of distances to every given point |
| 115 | Mixed Content | Separate words with digits |
| 116 | Morse Code | Decode Morse code |
| 018 | Multiples of a Number | Multiples of a number greater than another number |
| 023 | Multiplication Tables | Print out the grade school multiplication table upto 12*12 |
| 113 | Multiply Lists | Multiply elements in 2 lists |
| 062 | N Mod M | Determine the modulus (without the modulus operator) |
| 160 | Nice Angles | Convert angle values to sexagesimal format |
| 232 | Not So Clever | Simplicity is not always good |
| 025 | Odd Numbers | Print the odd numbers from 1 to 99 |
| 217 | One Zero, Two zeros... | Count zeros in a binary system |
| 237 | Panacea - Truth or Lie | Check whether the virus was stopped by antivirus |
| 092 | Penultimate Word | Find the next-to-last word |
| 003 | Prime Palindrome | Biggest prime palindrome < 1000 |
| 087 | Query Board | Set and get values from a matrix using tiny DSL |
| 136 | Racing Chars | Explore a race track avoiding crashes |
| 167 | Read More | Limit the length of the text |
| 227 | Real Fake | Check credit card numbers |
| 008 | Reverse Words | Reversing an input sequence of words |
| 031 | Rightmost Char | Print the position of the rightmost occurrence of a char |
| 124 | Road Trip | Do not be left without petrol |
| 156 | Roller Coaster | Turn the text into RoLlErCoAsTeR case |
| 106 | Roman Numerals | Convert a cardinal number to a Roman numeral |
| 040 | Self Describing Numbers | Determine if a number is a self-describing number or not |
| 030 | Set Intersection | Print the intersection of two sets of numbers |
| 107 | Shortest Repetition | Find the shortest repetition in a string |
| 235 | Simple or Trump | Check which card is higher |
| 091 | Simple Sorting | Sort several numbers |
| 174 | Slang Flavor | Add some slang to the text |
| 131 | Split the Number | Evaluate the number according to the pattern |
| 202 | Stepwise Word | Print the longest word in a stepwise manner |
| 199 | String Mask | Change case letters by mask |
| 203 | Strings and Arrows | Print the number of arrows in a string |
| 021 | Sum of Digits | Sum of digits comprising a number |
| 024 | Sum of Integers From File | Print the sum of integers read from a file |
| 004 | Sum of Primes | Sum of first 1000 primes |
| 096 | Swap Case | Swap case in a string |
| 112 | Swap Elements | Swap elements in a list |
| 196 | Swap Numbers | Swap numbers surrounding a word |
| 225 | Testing | Wanna try to be a tester? |
| 132 | The Major Element | Find the major element in a sequence |
| 214 | Time to Eat | Sort timestamps in the right order |
| 220 | Trick or Treat | Count all candies |
| 029 | Unique Elements | Extract unique list from a sorted list of numbers |
| 173 | Without Repetitions | Delete characters that are consistently repeated |
| 104 | Word to Digit | Substitute words to digits |
| 139 | Working Experience | Retrieve an actual value |
| CID | Name | Synopsis |
|---|---|---|
| 117 | A Pile of Bricks | Close a hole in a wall |
| 223 | Alternative Reality | Count all alternative ways |
| 041 | Array Absurdity | Determine if an array contains a duplicated entry |
| 084 | Balanced Smileys | Facebook Hacker Cup 2013 problem |
| 146 | Bats Challenge | Count bats on the wire |
| 236 | Beat or Bit | Learn more about the Gray code algorithm |
| 209 | Black or White | Find the smallest submatrix |
| 179 | Broken LCD | Determine whether a given number can be displayed on the damaged LCD |
| 218 | Builders Team | Count all squares on the map |
| 184 | Burrows-Wheeler Transform | Complete file decompression by inverting BWT |
| 138 | Car Race | Determine the fastest car |
| 172 | Card Number Validation | Check if bank card numbers are valid |
| 054 | Cash Register | Determine the amount of change to be returned |
| 119 | Chain Inspection | Try to pass a chain |
| 133 | City Blocks Flyover | Chart the path of a helicopter from above to discover how many city blocks it flew over |
| 238 | Code Combinations | Check whether you can make words from the given letters |
| 148 | Color Code Converter | Determine and convert the color code |
| 197 | Column Names | Convert integer to excel-style column name |
| 187 | Consecutive Primes | Determine how many ways the numbers can be arranged such that every consecutive pair sums to a prime |
| 063 | Counting Primes | Count the number of primes between two integers |
| 027 | Decimal to Binary | Print the binary representation of a decimal number |
| 073 | Decode Numbers | Count the number of ways to decode a string |
| 005 | Detecting Cycles | Detecting loops within a sequence |
| 033 | Double Squares | FaceBook Hacker Cup 2011: Output the number of ways to write X as the sum of two squares |
| 215 | Double Trouble | Calculate the number of correct variants for messages |
| 035 | Email Validation | Write a regular expression to validate an email address |
| 015 | Endianness | Determine the endianness of a system |
| 169 | Filename Pattern | Filter a list of filenames |
| 101 | Find a Square | Do 4 points make a square? |
| 012 | First Non-Repeated Character | Find the first non repeated character in a string |
| 075 | Flavius Josephus | Eliminate every i'th item from a circular list |
| 161 | Game of Life | Implement the classical cellular automaton game |
| 181 | Gronsfeld Cipher | Decipher the message enciphered with the Gronsfeld cipher |
| 170 | Guess the Number | Guess the number in log2(N) steps |
| 158 | Interrupted Bubble Sort | Sort a list of elements, partially |
| 043 | Jolly Jumpers | Determine if a sequence of numbers is a Jolly Jumper |
| 177 | Justify the Text | Align the text to the specified width |
| 153 | Locks | Calculate unlocked doors |
| 002 | Longest Lines | Finding the 'N' longest lines within a file |
| 121 | Lost in Translation | Try to become a native speaker |
| 011 | Lowest Common Ancestor | Determine the lowest common ancestor within a tree |
| 206 | Lucky Tickets | Count the lucky tickets |
| 193 | Magic Numbers | Print out a list of all the magic numbers in a provided range |
| 231 | Meet Cocktail Sort | Learn more about cocktail sort algorithm |
| 233 | Meet Comb Sort | Learn more about the comb sort algorithm |
| 074 | Minimum Coins | Find the minimum number of coins to arrive at a total |
| 010 | Mth to Last Element | Determine the Mth to last element of a list |
| 016 | Number of Ones | Determine the number of one bits in an integer |
| 190 | Number Operations | Determine if it is possible to produce the number 42 with five cards |
| 034 | Number Pairs | Find pairs of numbers in a sorted array whose sum is X |
| 221 | Organizational Hierarchy | Recreate the hierarchy tree |
| 070 | Overlapping Rectangles | Determine if two rectangles overlap |
| 037 | Pangrams | Find the missing alphabets |
| 066 | Pascals Triangle | Print out pascals triangle upto a certain depth |
| 089 | Pass Triangle | Lead the way within the triangle |
| 098 | Point in Circle | Define whether a point is in a circle |
| 125 | Predict the Number | Try to go beyond the limits |
| 046 | Prime Numbers | Print prime numbers less than N |
| 013 | Remove Characters | Delete specific characters from a string |
| 045 | Reverse and Add | Continually add a number to its reverse to arrive at a palindrome |
| 071 | Reverse Groups | Reverse elements in a list k items at a time |
| 212 | Robo and Robitta | Count all nuts |
| 150 | Roman and Arabic | Calculate aromatic numbers |
| 137 | Seek for an Intruder | Find the IP address of an intruder |
| 130 | Sequence Transformation | Transform a binary sequence into a string |
| 094 | Simple Calculator | Create a simple calculator |
| 200 | Sort Matrix Columns | Sort matrix columns from lowest to highest numbers |
| 009 | Stack Implementation | Implement a stack interface |
| 076 | String Rotation | Find if a string is the rotation of another string |
| 078 | Sudoku | Determine if a grid layout is a valid sudoku solution |
| 165 | Suggest Groups | Help your friends to join groups |
| 017 | Sum of Integers | Determine the largest sum of contiguous integers in an array |
| 081 | Sum to Zero | Count of ways in which the sum of four numbers is zero |
| 143 | The Ministry of Truth | Your task is to help the Big Brother |
| 228 | To PI or Not to PI | Print a PI number |
| 032 | Trailing String | Determine if a string 'B' occurs at the end of string 'A' |
| 226 | Try to Solve It | How good decoder are you? |
| 194 | Twenty Forty Eight | Implement the 2048 game logic |
| 080 | URI Comparison | Determine if two URIs match |
| 068 | Valid Parentheses | Determine if string is a well-formed parentheses |
| 135 | Word Chain | Find the longest chain of words |
| CID | Name | Synopsis |
|---|---|---|
| 134 | A Bus Network | Try to save more time |
| 095 | Advanced Calculator | Create an advanced calculator |
| 201 | Alphabet Blocks | Forming words from alphabet blocks |
| 239 | As Quick as a Flash | Learn more about the quick sort algorithm |
| 155 | ASCII Decryption | Decrypt a message |
| 109 | Bay Bridges | Build Bridges Over San Francisco Bay |
| 210 | Brainf*ck | Blow your mind |
| 064 | Climbing Stairs | Count the number of ways to climb to the top of a staircase |
| 051 | Closest Pair | Given a set of points in a two dimensional space, you will have to find the distance between the closest two points |
| 234 | Code Like Huffman | Learn more about Huffman's tree |
| 127 | Code Plagiarism | Compare source code of two programs |
| 090 | Commuting Engineer | Travelling Salesman Problem |
| 108 | Computer Terminal | Print text to terminal with control sequences |
| 151 | ing Eggs | Determine the number of drops |
| 195 | Crime House | Count criminals in the Crime House |
| 077 | Da Vyncy | Recreate a document from a set of fragments |
| 061 | Decryption | Determine the plain text message from an encrypted string |
| 144 | Digit Statistics | Find statistics in sequence |
| 048 | Discount Offers | Determine optimal pairing of customers with products |
| 069 | Distinct Subsequences | Determine the number of distinct subsequnces within a string |
| 188 | Distinct Triangles | Find the number of distinct triangles formed in a graph |
| 171 | DNA Alignment | Find the highest score of DNA sequences alignment |
| 123 | Efficient Delivery | Load your tankers with oil |
| 216 | Everything or Nothing | Check if a code is correct |
| 085 | Find Min | Facebook Hacker Cup 2013 problem |
| 141 | Flight 370 | Follow the current search results |
| 044 | Following Integer | Determine the next number in a sequence |
| 185 | Glue Shredded Pieces | Reconstruct the original text from overlapping pieces |
| 060 | Grid Walk | The number of grid points that can be accessed |
| 229 | Grinch | Help Grinch to find the shortest way |
| 154 | IP Package | Calculate IP checksum |
| 088 | Juggle Fest | A challenge from Yodle |
| 213 | Lakes, Not Cakes | Count all lakes |
| 105 | Largest Sub-Matrix | Determine the largest sub-matrix in a matrix |
| 198 | Less Money, More Problems | Help citizens by adding new coin denominations |
| 058 | Levenshtein Distance | Find out how big the social network of a word is |
| 191 | Lights Out | Switch all the lights off with minimum number of moves |
| 006 | Longest Common Subsequence | LCS between two strings |
| 182 | Longest Path | Find the longest path of unique elements |
| 164 | Mars Networks | Find the minimum length of the optical fiber cable which connects probes to a network |
| 036 | Message Decoding | Decode an encoded message |
| 079 | Minesweeper | Find the mines within a M*N matrix |
| 072 | Minimum Path Sum | Calculate the minimum sum of a path through a matrix |
| 114 | Package Problem | Put as many things into a package as possible |
| 047 | Palindromic Ranges | Find out a range of palindromic numbers |
| 049 | Peak Traffic | Finding out which friends you interact with most |
| 126 | Play With DNA | Write an algorithm that a finds DNA segment in a given DNA string |
| 086 | Poker Hands | Compare two poker hands |
| 007 | Prefix Expressions | Evaluating a prefix expression |
| 224 | Prisoner or Citizen | In jail or at large? |
| 176 | Ray of Light | Trace the path of light distribution |
| 053 | Repeated Substring | Find the longest repeated substring in a given text |
| 056 | Robot Movements | Number of ways a robot can reach its destination |
| 129 | Routing Problem | Find all the shortest paths for the package between two specified hosts |
| 145 | Running for President | Build your strategy to win the Presidency of the United States |
| 118 | Seat Your Team Members | Place the employees in a new office |
| 120 | Skyscrapers | Outline skyscrapers in a city |
| 057 | Spiral Printing | Print out a 2D array in spiral order |
| 204 | Straight Lines | Print the number of straight lines |
| 038 | String List | Create a new string from constituent alphabets |
| 014 | String Permutations | Print out all permutations of a string |
| 028 | String Searching | Determine if substring match exists |
| 050 | String Substitution | Create a new string by replacing substrings within it |
| 059 | Telephone Words | Print out the words corresponding to a telephone number |
| 052 | Text Dollar | Print out the text dollar amount of a given quantity |
| 110 | Text to Number | Convert English text representation of a number to a decimal number |
| 175 | The Cubes | Find the length of the shortest way in the multilevel labyrinth |
| 168 | The Frequency | Find the signals frequency |
| 157 | The Labyrinth | Find the shortest way to exit |
| 219 | The Tourist | Find the shortest route between cities |
| 162 | Too Unique | Find and mark the biggest submatrices of unique elements |
| 055 | Type Ahead | Building a type ahead feature |
| 042 | Ugly Numbers | Count the number of expressions that can be created from a number |
| 142 | Visit to the Headquarters | Organize the queues |
| 159 | Where Is Wi-Fi | Find out in which buildings there are hotspots |
| 207 | Which Way Is Faster? | Find the fastest way |
| 065 | Word Search | Find if a word exists in a grid |
All original work is released under the MIT license, unless otherwise specified.
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