# Problem Solutions

Here we discuss the solutions of problems.

Do not forget to make the topic "private" and specify problem number so that other users can only see it after they solve this problem!

Creating new topics is allowed after you solve at least 5 problems!

Topic Posts Created Last post
[Task#113] How to solve Ground Zero 5 Aug 3 2014 Jan 26 2018 01:26
Task 18 - Square Root 3 Jan 23 2018 Jan 23 2018 16:28
Problem 206 Base-32 Encoding 1 Jan 22 2018 Jan 22 2018 23:59
Error in 114 Gradient Descent for SLE 3 Mar 13 2015 Jan 7 2018 12:50
Median of 2 2 Dec 15 2017 Dec 15 2017 23:57
Neumanns Random Generator 8 Nov 19 2017 Nov 22 2017 12:22
Problem 34 Binary Search 20 Jan 20 2015 Nov 13 2017 19:56
[190] Query String Parameters 3 Apr 4 2015 Nov 7 2017 20:21
Problem 69 - Fibonacci Divisibility - are input values valid? 5 Oct 27 2017 Oct 30 2017 10:44
problem in submission task 147 Color Cubes Advanced 3 Oct 20 2017 Oct 20 2017 20:36
Problem 127 - Anagram 8 Apr 3 2015 Sep 28 2017 15:28
[C] Problem 67 Fibonacci sequence 5 Aug 2 2017 Sep 28 2017 06:30
Problem 14 Modular Calculator 2 Aug 31 2017 Aug 31 2017 19:50
Problem 34 Binary search precision 7 Aug 18 2017 Aug 18 2017 15:32
Neumanns Random Generator 2 Aug 7 2017 Aug 7 2017 07:52
Pairing Control problem 5 Aug 3 2017 Aug 3 2017 23:24
[45 Card Shuffler] Doesnt Random mean different results? 2 Jul 15 2017 Jul 15 2017 04:20
[Task#180] Is Simple Game of Sticks really simple? 6 Dec 6 2014 Jul 12 2017 22:18
Smoothing the weather - Java precision 3 May 25 2017 Jun 3 2017 09:18
Problem 66 Caesar Cipher Cracker 1 May 2 2017 May 2 2017 10:33
[Problem 187] Static Web Page - No HTTPS 1 Apr 30 2017 Apr 30 2017 22:45
Arithmetic Progression some problems 3 Mar 25 2017 Apr 3 2017 20:25
[Task#112] Travelling Salesman Inverted 2 Feb 19 2017 Apr 3 2017 20:15
[Problem 36] Code Guessser 11 Jan 20 2017 Mar 29 2017 08:58
Fibonacci positions (task 67) in JavaScript 11 Aug 2 2015 Mar 24 2017 01:25
[Task83] Graph Generator 3 Mar 10 2017 Mar 14 2017 08:56
22 Two Printers 4 Feb 5 2017 Feb 6 2017 19:50
[Task#6] Problems with Rounding 4 Jan 28 2017 Jan 30 2017 14:13
[Task#51] [Problem 51] Dungeons and Dragon Dice 1 Jan 30 2017 Jan 30 2017 12:09
Page Rank as Eigenvector 4 Jan 15 2016 Jan 30 2017 07:03
[Problem 131] Four Pics One Word 3 Jan 27 2017 Jan 28 2017 04:31
[Task#43] Dice Rolling 2 Jan 16 2017 Jan 24 2017 21:04
Luhn Algorithm need help 3 Jan 21 2017 Jan 21 2017 13:59
Parity Control 3 Jan 8 2017 Jan 8 2017 10:39
[Task#213] Micro-Life ranking system 8 Nov 11 2015 Jan 3 2017 21:12
[Task#20] Clumsy solution 2 Jan 3 2017 Jan 3 2017 19:13
Modular Calculator 7 Jun 30 2015 Dec 22 2016 19:31
Problem 54 - Pythagorean Triples 3 Dec 17 2016 Dec 18 2016 20:40
Problem 117 Divide by Two 6 Jun 29 2016 Dec 15 2016 17:37
[Task#212] How to calc the solution size 10 Oct 8 2015 Dec 15 2016 07:58
46 Tic-Tac-Toe Problem statement 3 Dec 12 2016 Dec 12 2016 09:03
A little problem with array checksums using PHP 3 Dec 9 2016 Dec 10 2016 08:51
basic html 2 Nov 29 2016 Nov 29 2016 13:56
[Task#21] Array Counters 3 Nov 25 2016 Nov 25 2016 17:23
Median of three 3 Nov 21 2016 Nov 21 2016 16:18
Array CheckSum What is wrong? 8 Nov 8 2016 Nov 12 2016 00:20
Task 59 Bulls and Cows 3 Nov 3 2016 Nov 3 2016 11:26
[Task 23] Error when calculating array checksum 3 Aug 19 2016 Oct 12 2016 19:34
[Task#108] Star Medals what is the core idea of this task? (Star Medals 108) 3 Oct 5 2016 Oct 7 2016 11:03
46 Tic-Tac-Toe one in 17 answers is wrong What am I missing? 2 Oct 4 2016 Oct 5 2016 17:26
help with interactive http tasks 3 Oct 4 2016 Oct 4 2016 13:14
Issues connecting to interactive problem server? 3 Jul 13 2016 Sep 29 2016 11:00
Share price volatility - Standard deviation issue task 39 2 Sep 27 2016 Sep 27 2016 18:42
Most Frequent Word (Task 70) 10 Sep 19 2015 Sep 22 2016 19:56
Problem 61 - Prime Numbers Generation 7 Nov 9 2014 Sep 11 2016 19:25
Safe landing 4 Sep 3 2016 Sep 4 2016 09:39
Rotate string the answer tallies But shows it is wrong 4 Aug 30 2016 Sep 3 2016 15:21
Billiard Ball bounce from bottom and right borders problem 10 Aug 26 2016 Aug 27 2016 15:58
Clarifying the task --- Breadth First Search --- Task 154 14 Aug 24 2016 Aug 26 2016 13:22
Need help(task 22) 5 Aug 26 2016 Aug 26 2016 12:07
Problem 35 Savings Calculators 3 Aug 10 2016 Aug 10 2016 12:24
Bubble Sort 3 Aug 7 2016 Aug 7 2016 13:51
Problem 78 (Bezier Curves) 2 Aug 1 2016 Aug 1 2016 00:56
Depth First Search 10 Jul 24 2015 Jul 14 2016 09:22
Is there a mistake in example for problem 156 (Task Luhn Algorithm) 3 Jul 6 2016 Jul 7 2016 11:47
fibbonacci squared but this always field 2 Jun 17 2016 Jun 20 2016 15:25
Say-100 request 1 Jun 17 2016 Jun 17 2016 14:04
[task 18] on C Sharp 4 Jun 2 2016 Jun 7 2016 14:20
Example for the Cows and Pigs problem is incorrect 2 Jun 2 2016 Jun 3 2016 20:30
[Task#208] Known string neighborhood searching algorithms 1 May 26 2016 May 26 2016 18:55
Problem 141 description 16 Aug 7 2014 May 22 2016 17:20
Task 16 Average of an Array - Cplusplus 5 May 2 2016 May 4 2016 14:34
problem with task 24 2 Apr 25 2016 Apr 25 2016 19:00
Problem 27 Bubble Sort help 4 Nov 13 2015 Apr 25 2016 11:50
Problem 66 my code doesnt decipher all sentences dont know whats wrong 2 Apr 16 2016 Apr 24 2016 14:32
Problem 176 - getting the right answer but always losing the game - Python3 2 Apr 7 2016 Apr 7 2016 17:55
Color Cubes Advanced 2 Apr 2 2016 Apr 4 2016 08:21
Problem 8 [Java] 1 Apr 3 2016 Apr 3 2016 12:31
Aglae Robot 3 Apr 1 2016 Apr 1 2016 12:55
[Task#21] Array Counter - Quick Question 3 Mar 22 2016 Mar 23 2016 16:03
[Task#165] [problem 165] Safe Landing - Dont know whats wrong with my code 4 Mar 22 2016 Mar 22 2016 11:10
[Task#150] Introducing Regexps 2 Mar 13 2016 Mar 20 2016 05:41
[Task#118] Single-Player Maxit 1 Mar 20 2016 Mar 20 2016 02:06
[Task#61] Prime numbers generator c sharp 7 Aug 6 2015 Mar 14 2016 21:47
LZ77_decompression 1 Mar 11 2016 Mar 11 2016 16:40
Problem 57 Smoothing the Weather 3 Mar 10 2016 Mar 11 2016 15:55
Problem 33 4 Feb 20 2016 Mar 9 2016 22:29
Problem 67 6 Aug 27 2014 Mar 3 2016 19:36
Bubble in Array java 3 Feb 29 2016 Mar 1 2016 02:43
Calculation of Pi 6 Sep 27 2015 Feb 26 2016 19:42
Help with Shannon-Fano Coding 2 Feb 23 2016 Feb 24 2016 10:49
156 Luhn Algorithm 3 Feb 19 2016 Feb 21 2016 12:07
Problem 36 2 Feb 20 2016 Feb 21 2016 06:38
Problem 35 3 Feb 20 2016 Feb 20 2016 16:56
Selection Sort (120) 3 Feb 17 2016 Feb 17 2016 15:40
task 23 Bubble in Array 3 Feb 15 2016 Feb 16 2016 16:56
Problem 22 2 Feb 14 2016 Feb 14 2016 19:33
Some numbers do not match on 81 (Bit Count) 3 Feb 4 2016 Feb 4 2016 22:12
Look and Say Binary 179 4 Jan 31 2016 Feb 2 2016 12:59
NimGame 177 2 Jan 29 2016 Jan 30 2016 07:55
[Task#69] Fibonacci Divisibility 3 Jan 28 2016 Jan 29 2016 06:10
Query String Parameters --- the checker wont accept my URL Why? 6 Jan 20 2016 Jan 21 2016 19:25
Weighted sum of digits 6 Jan 16 2016 Jan 18 2016 20:57
Help with Bezier Curve (78) 1 Jan 18 2016 Jan 18 2016 17:05
Uphill Shooting (99) 7 Jan 8 2016 Jan 10 2016 08:09
Dynamic Web Page 2 Jan 7 2016 Jan 7 2016 14:11
Help with 32 Josephus Problem 6 Aug 11 2014 Jan 7 2016 11:40
Problem 163 Colliding Balls 9 Feb 8 2015 Jan 5 2016 15:39
Frodo and Black Riders 5 Jan 2 2016 Jan 3 2016 02:39
24 neumanns 3 Jan 1 2016 Jan 2 2016 16:01
[Task#19] 19 - Matching Brackets 1 Dec 31 2015 Dec 31 2015 19:17
Possible error or unexplained feature? 2 Dec 28 2015 Dec 28 2015 23:16
Problem 20 vowel count 9 Dec 22 2015 Dec 28 2015 09:21
17 Array Checksum 3 Dec 25 2015 Dec 26 2015 15:25
Binary Search in Array - IP database problem 3 Nov 4 2014 Dec 22 2015 15:03
Easter Eggs 5 Dec 8 2015 Dec 11 2015 14:41
task 33 Parity Control --- one space symbol before the answer 1 Dec 9 2015 Dec 9 2015 14:43
Average of an array rounding problem 7 Jun 27 2015 Dec 8 2015 08:55
Travelling Salesman 1 Dec 6 2015 Dec 6 2015 21:35
Help with Rounding (task 6) 5 Oct 24 2014 Dec 5 2015 08:01
Task 13 - Weighted sum of digits 4 Dec 1 2015 Dec 2 2015 19:24
Combinations counting (task 128) - Whats wrong with my code? 6 Oct 13 2014 Nov 30 2015 08:40
Problem 15 Max Array - Results match expected but still wrong 2 Nov 29 2015 Nov 29 2015 21:32
[Task#192] Gangster Battles 3 Nov 19 2015 Nov 20 2015 19:57
Problem 144 Modular Inverse - sometimes solutions exist 2 Nov 18 2015 Nov 19 2015 05:39
Random Search Optimization - transition problems? 1 Nov 18 2015 Nov 18 2015 16:56
17 problem? 4 Nov 16 2015 Nov 16 2015 20:29
Girls and pigs - just a note 2 Nov 12 2015 Nov 12 2015 15:51
[Task#33] I thought I would get a cool secret message D 4 Mar 19 2015 Nov 6 2015 21:18
[Task#204] Wandering Star Algorithm 5 Mar 11 2015 Nov 6 2015 11:21
Java error on this site 2 Nov 6 2015 Nov 6 2015 11:20
[Task#169] Automated Landing answer precision 4 Oct 28 2014 Nov 6 2015 05:40
Problem 21 ? 5 Nov 4 2015 Nov 4 2015 13:19
[Task#166] Page Rank as an Eigenvector 4 Oct 19 2015 Nov 3 2015 09:18
Task173 - Chords of music 4 Oct 19 2015 Oct 20 2015 07:04
[Task#23] Problem with Task 23 Two printers 6 Oct 16 2015 Oct 16 2015 14:44
Cards Shuffling Problem 45 5 Oct 11 2015 Oct 14 2015 14:44
Employees Web App (task 199) 3 Oct 9 2015 Oct 9 2015 06:39
Frodo and Black Riders 15 Oct 2 2015 Oct 3 2015 12:16
Suffix Array Advanced 4 Oct 2 2015 Oct 3 2015 09:48
[Task#169] Check this out 3 Oct 1 2015 Oct 2 2015 09:50
Problem 09 Java 3 Sep 30 2015 Oct 1 2015 15:06
Crossing the Road 5 Sep 28 2015 Sep 29 2015 06:26
Card Shuffling (task 45) 4 Sep 21 2015 Sep 22 2015 09:02
[Task#40] Paths in the Grid - Feedback? (Task 40) 6 Sep 12 2015 Sep 19 2015 21:16
Problem 14 C 15 Aug 12 2015 Sep 19 2015 11:11
Clarification for 210 Ticket Puzzle 7 Aug 30 2015 Aug 30 2015 15:59
Problem 33 Parity Control 5 Aug 15 2015 Aug 16 2015 06:23
Bicycle Race Examples 1 Aug 14 2015 Aug 14 2015 20:03
Difficulty solving problem 23 bubble in array 3 Aug 13 2015 Aug 13 2015 23:21
[Problem 67] Problem in C with size of input 8 Dec 14 2014 Aug 12 2015 06:45
Task 67 - Test-cases exceed range of long type (java) 5 Aug 11 2015 Aug 11 2015 17:05
Problem 176 interactive problem Sending correct answer but always end up losing game 6 Aug 8 2015 Aug 8 2015 09:45
Bubble in Array-- my algorithm solves the example lists but not the test case 4 Aug 4 2015 Aug 4 2015 19:20
Neumanns Random Generator 3 Aug 2 2015 Aug 2 2015 17:09
[Task#12] Modulo and time difference - request for code review (Python) 5 Jul 27 2015 Jul 28 2015 10:06
Easter Eggs 5 Jul 24 2015 Jul 24 2015 12:18
Gradient Calculation (task 101) 2 Jul 23 2015 Jul 23 2015 10:42
17 Array Checksum - Is my checksum algorithm correct? 3 Jul 21 2015 Jul 21 2015 21:05
[Task#80] Problem 80 Solution Explaination 5 Jul 19 2015 Jul 19 2015 21:13
[Task#205] Problem with Clustering the Stars checker 2 Jul 19 2015 Jul 19 2015 14:20
[14] [C] How do we deal with large intermediate numbers? 6 Jul 18 2015 Jul 18 2015 21:53
Clustering the Stars 1 Jul 18 2015 Jul 18 2015 17:24
[Important] Problem 104 Solution Explanation - Spoiler alert 3 Jul 17 2015 Jul 17 2015 16:08
Array Counter (task 21) 4 Jul 13 2015 Jul 15 2015 20:32
Gradient Calculation 13 Jul 9 2015 Jul 11 2015 10:17
[Task#50] Palindrome problem 6 Jul 7 2015 Jul 10 2015 10:15
Triangle Area rounding problem 3 Jul 1 2015 Jul 8 2015 11:00
Im doing something wrong? 14 Jun 26 2015 Jul 2 2015 15:36
Task14 Problem 3 Jun 29 2015 Jun 29 2015 10:39
Unable to do the maths behind problem 10 2 Jun 27 2015 Jun 27 2015 19:01
DungeonsAndDragonsDice 6 Jun 24 2015 Jun 25 2015 21:55
Flying Text Screensaver 2 Jun 21 2015 Jun 22 2015 11:53
Task 144 Explanation 3 May 31 2015 Jun 8 2015 21:50
Problem 119 Brain Fibo 2 Jun 4 2015 Jun 8 2015 20:40
Girls and pigs number of solutions 4 May 19 2015 May 25 2015 06:41
Is the testing system works as it should? 3 May 21 2015 May 21 2015 23:30
Problem 22 2 May 15 2015 May 17 2015 06:32
A question about Problem 119 Brain Fibo 3 May 1 2015 May 1 2015 22:41
[Task 80] explanation on authors notes on the problem ? 4 Apr 20 2015 Apr 29 2015 06:32
[Task#103] Easter Eggs 4 Jan 20 2015 Apr 29 2015 06:30
[Task#104] Triangle Area revision on authors notes 1 Apr 15 2015 Apr 15 2015 20:49
Task 14 - C - Getting wrong solution and unable to locate why 3 Apr 12 2015 Apr 12 2015 20:57
[Task 35] Savings Calculator wrong result ? 6 Apr 9 2015 Apr 10 2015 05:31
Task 14 - Im getting the wrong result and I dont know why Help 3 Apr 6 2015 Apr 7 2015 10:20
[187] Static Web Page 2 Apr 3 2015 Apr 6 2015 08:54
Problem 40 Paths in the Grid - No Output? 4 Mar 31 2015 Apr 5 2015 02:39
Two Printers 9 Dec 26 2014 Mar 25 2015 00:11
Task 13 - Weighted sum of digits 12 Feb 17 2015 Mar 4 2015 10:35
What wrong with dancing pairs? 7 Feb 22 2015 Feb 23 2015 14:36
Enumerating Combinations (task 129) 6 Feb 16 2015 Feb 21 2015 07:47
[Task#201] What I have done 7 Feb 19 2015 Feb 20 2015 19:45
[Task#86] Simple brainfk interpreter (private) 3 Feb 13 2015 Feb 13 2015 18:09
Fibonacci Divisibility (69) - long numbers 5 Feb 1 2015 Feb 3 2015 08:39
My problem with Dynamic Web Page at PythonAnywhere 5 Feb 1 2015 Feb 2 2015 21:04
Problem with PythonPrintHexStr task 3 Feb 1 2015 Feb 1 2015 08:45
Hexagonal Grid 7 Jan 29 2015 Jan 29 2015 20:49
[Task#199] Employees Web App 3 Jan 28 2015 Jan 28 2015 14:54
[Task#193] Maximum Flow 3 Jan 18 2015 Jan 19 2015 14:56
Tricky Printing - Brainfuck problem 3 Jan 17 2015 Jan 17 2015 17:47
task 16 Average of an array I dont get why this rounding doesnt work 2 Jan 17 2015 Jan 17 2015 17:18
Flow Network 6 Jan 17 2015 Jan 17 2015 17:07
[Task#36] code guesser Did anyone solve it a better way 4 Jan 4 2015 Jan 15 2015 10:32
Problems with problem 116 5 Aug 18 2014 Jan 12 2015 15:45
[Task#14] What is the use of this problem? 2 Jan 12 2015 Jan 12 2015 13:09
Static Web Page - https 3 Jan 8 2015 Jan 8 2015 20:05
Prime Chains 12 Aug 20 2014 Dec 24 2014 13:22
[Problem 50] CPU time limit exceeded (core dumped) 3 Dec 21 2014 Dec 22 2014 14:36
Counting Vowels Problem 3 Dec 4 2014 Dec 4 2014 07:56
[Task#128] Combinations Counting 4 Nov 30 2014 Dec 1 2014 15:42
DFS works fine with example but still fails (Task 155) 4 Nov 26 2014 Dec 1 2014 13:28
[Task#31] Rotate String 4 Nov 25 2014 Nov 29 2014 11:40
[Task#179] Look and Say binary 3 Nov 28 2014 Nov 28 2014 13:27
[Task#178] Maze of the Wumpus - methods to generate maze 2 Nov 24 2014 Nov 24 2014 10:15
C Sharp Problem 67 2 Nov 19 2014 Nov 20 2014 06:04
[Task#175] Algae Robot - tips and trics 4 Nov 19 2014 Nov 19 2014 15:08
Sequence of Squares (task 126) 3 Nov 15 2014 Nov 16 2014 07:36
[Task#174] The last digits 3 Nov 13 2014 Nov 13 2014 21:05
[Task#173] Chords of Music - test data correctness 7 Nov 10 2014 Nov 11 2014 14:06
Bit Count confusion (task 81) 11 Nov 6 2014 Nov 9 2014 16:05
159 Hard Life confirmation 8 Oct 5 2014 Nov 7 2014 16:15
[Task#167] BF - Copy Line 3 Oct 24 2014 Oct 26 2014 05:49
[Task#168] Caesar meets BF 11 Oct 21 2014 Oct 22 2014 05:37
[Task#167] Copy Line checker 8 Oct 20 2014 Oct 21 2014 08:18
[Task#159] Hard Life Solutions 3 Oct 6 2014 Oct 7 2014 04:39
Hamming Codes 3 Sep 16 2014 Sep 16 2014 13:37
Palindromic Primes 19 Sep 5 2014 Sep 8 2014 11:27
[Task#155] Solution visualization 6 Sep 3 2014 Sep 4 2014 10:44
problem 57 6 Aug 25 2014 Aug 26 2014 18:05
[Task#151] Word Ladders solving methods 13 Aug 23 2014 Aug 25 2014 12:09
Introducing Regexps - minor problems 5 Aug 22 2014 Aug 22 2014 17:56
[Task#147] Color Cubes Advanced 6 Aug 19 2014 Aug 19 2014 21:41
[Task#145] Two solutions for task 145 12 Aug 12 2014 Aug 13 2014 01:55
[Task#145] Task 145 is that OK Oh and its really looks nothing like Python 2 Aug 12 2014 Aug 12 2014 09:39
[Task#144] Another algorithm for Task 144 private 1 Aug 12 2014 Aug 12 2014 08:04
Modular Inverse unittest 11 Aug 11 2014 Aug 11 2014 15:55
Minor corrections for 143 and 144 2 Aug 11 2014 Aug 11 2014 11:06
Correction in Task 124 2 Aug 9 2014 Aug 9 2014 05:07