The Gray Code Decoder and Gray Code Encoder holes will go live in approximately 4 days. Why not try and solve them ahead of time?
Card Number Validation in all languages in chars. Achievements Cheevos Holes Languages Medals Miscellaneous All Holes 12 Days of Christmas 24 Game 99 Bottles of Beer Abundant Numbers Abundant Numbers (Long) Arabic to Roman Arithmetic Numbers Arrows Ascending Primes ASCII Table Billiards brainfuck Calendar Card Number Validation Catalan Numbers Catalan’s Constant Christmas Trees Collatz Continued Fractions CSS Colors Cubes Day of Week DFA Simulator Diamonds Divisors Emirp Numbers Emirp Numbers (Long) Emojify Evil Numbers Evil Numbers (Long) Factorial Factorisation Farey Sequence Fibonacci Fizz Buzz Foo Fizz Buzz Bar Forsyth–Edwards Notation Fractions Game of Life Gijswijt’s Sequence Happy Numbers Happy Numbers (Long) Hexdump Hilbert Curve Intersection Inventory Sequence ISBN Jacobi Symbol Kaprekar Numbers Kolakoski Constant Kolakoski Sequence Leap Years Levenshtein Distance Leyland Numbers ln 2 Look and Say Lucky Numbers Lucky Tickets Mahjong Mandelbrot Maze Medal Tally Minesweeper Morse Decoder Morse Encoder Multitap Input Musical Chords N Queens Niven Numbers Niven Numbers (Long) Number Spiral Odious Numbers Odious Numbers (Long) Ordinal Numbers PalindromemordnilaP Pangram Grep Partition Numbers Pascal’s Triangle Pernicious Numbers Pernicious Numbers (Long) Poker Polyominoes Prime Numbers Prime Numbers (Long) Proximity Grid QR Decoder Quine Recamán Repeating Decimals Reverse Polish Notation Reversi Rijndael S-box Rock-paper-scissors-Spock-lizard Roman to Arabic ROT13 Rule 110 Scrambled Sort Set Seven Segment SI Units Sierpiński Triangle Smith Numbers Spelling Numbers Star Wars GPT Star Wars Opening Crawl Sudoku Sudoku (Fill-in) Ten-pin Bowling Tic-tac-toe Time Distance Tongue-twisters Topological Sort Tower of Hanoi Transpose Sentence Trinomial Triangle United States Vampire Numbers Van Eck Sequence Zeckendorf Representation Zodiac Signs γ λ π τ φ √2 𝑒 Alphabetic Numbers Apéry’s Constant Binary Lambda Calculus Connect Four Crossword CSS Colors (Inverse) CSS Grid Ellipse Perimeters Flags Floyd-Steinberg Dithering Gray Code Decoder Gray Code Encoder Hexagonal Spiral Highly Composite Numbers NFA Simulator Numbrix Odd Polyomino Tiling p-adic Expansion Polygon Triangulations QR Encoder Quadratic Formula Rectangle Fill Semiprime Numbers Smooth Numbers Snake Sphenic Numbers Taxicab Numbers Turtle Tutorial All Languages ><> ALGOL 68 ArkScript Assembly AWK Bash BASIC Berry brainfuck C C# C++ Civet Clojure COBOL Coconut Common Lisp Crystal D Dart Elixir Erlang F# Factor Forth Fortran Gleam Go GolfScript Groovy Haskell Hexagony J Janet Java JavaScript jq Julia K Kotlin Lua Nim OCaml Pascal Perl PHP PowerShell Prolog Python R Raku Rockstar Ruby Rust Scheme sed SQL Swift Tcl TeX V VimL Wren Zig 05AB1E APL Arturo Befunge BQN CJam CoffeeScript Egel Fennel Harbour Hare Haxe Hush Hy iogii Knight Lily Luau Odin Picat Qore Racket Rebol Rexx Scala Squirrel Stax Uiua Umka Vala Vyxal Bytes Chars Scoring Bytes Chars Language All ><> ALGOL 68 ArkScript Assembly AWK Bash BASIC Berry brainfuck C C# C++ Civet Clojure COBOL Coconut Common Lisp Crystal D Dart Elixir Erlang F# Factor Forth Fortran Gleam Go GolfScript Groovy Haskell Hexagony J Janet Java JavaScript jq Julia K Kotlin Lua Nim OCaml Pascal Perl PHP PowerShell Prolog Python R Raku Rockstar Ruby Rust Scheme sed SQL Swift Tcl TeX V VimL Wren Zig Experimental Language 05AB1E APL Arturo Befunge BQN CJam CoffeeScript Egel Fennel Harbour Hare Haxe Hush Hy iogii Knight Lily Luau Odin Picat Qore Racket Rebol Rexx Scala Squirrel Stax Uiua Umka Vala Vyxal Hole All 12 Days of Christmas 24 Game 99 Bottles of Beer Abundant Numbers Abundant Numbers (Long) Arabic to Roman Arithmetic Numbers Arrows Ascending Primes ASCII Table Billiards brainfuck Calendar Card Number Validation Catalan Numbers Catalan’s Constant Christmas Trees Collatz Continued Fractions CSS Colors Cubes Day of Week DFA Simulator Diamonds Divisors Emirp Numbers Emirp Numbers (Long) Emojify Evil Numbers Evil Numbers (Long) Factorial Factorisation Farey Sequence Fibonacci Fizz Buzz Foo Fizz Buzz Bar Forsyth–Edwards Notation Fractions Game of Life Gijswijt’s Sequence Happy Numbers Happy Numbers (Long) Hexdump Hilbert Curve Intersection Inventory Sequence ISBN Jacobi Symbol Kaprekar Numbers Kolakoski Constant Kolakoski Sequence Leap Years Levenshtein Distance Leyland Numbers ln 2 Look and Say Lucky Numbers Lucky Tickets Mahjong Mandelbrot Maze Medal Tally Minesweeper Morse Decoder Morse Encoder Multitap Input Musical Chords N Queens Niven Numbers Niven Numbers (Long) Number Spiral Odious Numbers Odious Numbers (Long) Ordinal Numbers PalindromemordnilaP Pangram Grep Partition Numbers Pascal’s Triangle Pernicious Numbers Pernicious Numbers (Long) Poker Polyominoes Prime Numbers Prime Numbers (Long) Proximity Grid QR Decoder Quine Recamán Repeating Decimals Reverse Polish Notation Reversi Rijndael S-box Rock-paper-scissors-Spock-lizard Roman to Arabic ROT13 Rule 110 Scrambled Sort Set Seven Segment SI Units Sierpiński Triangle Smith Numbers Spelling Numbers Star Wars GPT Star Wars Opening Crawl Sudoku Sudoku (Fill-in) Ten-pin Bowling Tic-tac-toe Time Distance Tongue-twisters Topological Sort Tower of Hanoi Transpose Sentence Trinomial Triangle United States Vampire Numbers Van Eck Sequence Zeckendorf Representation Zodiac Signs γ λ π τ φ √2 𝑒 Experimental Hole Alphabetic Numbers Apéry’s Constant Binary Lambda Calculus Connect Four Crossword CSS Colors (Inverse) CSS Grid Ellipse Perimeters Flags Floyd-Steinberg Dithering Gray Code Decoder Gray Code Encoder Hexagonal Spiral Highly Composite Numbers NFA Simulator Numbrix Odd Polyomino Tiling p-adic Expansion Polygon Triangulations QR Encoder Quadratic Formula Rectangle Fill Semiprime Numbers Smooth Numbers Snake Sphenic Numbers Taxicab Numbers Turtle Tutorial # Golfer Points Chars Time Submitted 721st owen-c-parker 🇺🇸 492 131 11ms 1 Oct 2024 722nd HumanoidCPU 492 145 480ms 5 Oct 2024 723rd h-hh-hhh 🇺🇦 491 177 70ms 2 Nov 2024 724th snoozingnewt 🇨🇦 491 249 26ms 2 Nov 2025 725th snoozingnewt 🇨🇦 490 150 219ms 2 Nov 2025 726th jlangvand 488 141 1ms 15 Oct 2024 726th HumanoidCPU 488 141 1ms 7 Mar 2025 728th snoozingnewt 🇨🇦 486 117 1,338ms 2 Nov 2025 729th Mabeloid 🇳🇴 486 133 11ms 2 Oct 2024 730th mitzal 483 180 70ms 9 Feb 2025 731st snoozingnewt 🇨🇦 482 173 377ms 2 Nov 2025 732nd denkyuu1 477 118 287ms 6 hours ago 733rd MiffOttah 476 150 478ms 6 Oct 2024 733rd mwarvik 🇳🇴 476 150 431ms 1 Jan 2026 735th sciencedjinn 475 136 10ms 8 Nov 2024 735th jastrzumb 475 136 18ms 4 Jan 2025 735th Florian-Mt 475 136 17ms 5 Dec 2025 738th alphafalfa 472 92 2ms 8 Nov 2024 739th kurkale6ka 472 137 22ms 16 Oct 2024 739th 4ndyJ 🇬🇧 472 137 11ms 14 Nov 2024 739th Mikey-Beep 🇬🇧 472 137 17ms 6 Aug 2025 739th wobblybits 472 137 19ms 17 Aug 2025 739th Andrey2001 472 137 9ms 1 Feb 2026 739th tomh1012 472 137 17ms 22 days ago 739th Aquateraneal 🇺🇸 472 137 17ms 18 days ago 746th luca1339 472 198 425ms 4 Nov 2024 747th ejini6969 469 102 39ms 14 Jun 2025 748th h-hh-hhh 🇺🇦 468 147 1ms 2 Nov 2024 749th snoozingnewt 🇨🇦 467 200 230ms 2 Nov 2025 750th snoozingnewt 🇨🇦 465 121 229ms 27 Nov 2025 751st scpchicken 🇵🇼 465 139 17ms 6 Oct 2024 752nd iczelia 🇩🇪 462 94 2ms 23 Sep 2025 753rd NanduBC 462 140 9ms 1 Oct 2024 753rd jmerle 🇳🇱 462 140 10ms 10 Jan 2025 753rd RobertHoeh 462 140 11ms 3 Mar 2025 753rd smilesformiles3 462 140 17ms 12 Jun 2025 753rd artem-aramma 462 140 18ms 18 Jun 2025 758th Jacob385 462 202 418ms 2 Oct 2024 759th madex 🇩🇪 460 104 37ms 2 Oct 2024 760th FranklinJiaChen 458 141 10ms 2 Oct 2024 761st TheZwierzLF 🇵🇱 456 105 37ms 8 Jan 2026 762nd jbjd 456 151 2ms 4 Feb 2026 763rd brimstonetrader 455 142 11ms 17 Oct 2024 763rd codewrite 🇬🇧 455 142 10ms 5 May 2025 763rd RobGLambert 455 142 17ms 8 Jun 2025 763rd GodlyProgrammer1 455 142 18ms 22 Nov 2025 763rd jbjd 455 142 11ms 4 Feb 2026 768th snoozingnewt 🇨🇦 455 149 5ms 2 Nov 2025 769th IISResetMe 453 103 583ms 27 Nov 2025 770th TheZwierzLF 🇵🇱 453 127 507ms 12 Dec 2025 771st snoozingnewt 🇨🇦 452 96 2ms 2 Nov 2025 772nd GeneralFabian 452 143 10ms 9 Dec 2024 772nd CutSandstone 452 143 10ms 30 Jan 2025 772nd kistlerf 🇨🇭 452 143 17ms 19 May 2025 775th dokutan 451 63 3ms 26 Nov 2024 776th snoozingnewt 🇨🇦 451 176 2ms 2 Nov 2025 777th hiichbindermax 449 144 17ms 2 Oct 2024 777th mathisfun271 449 144 10ms 14 Oct 2024 777th bob-th 449 144 10ms 22 Oct 2024 780th Andrey2001 446 129 525ms 1 Feb 2026 781st dokutan 445 109 10ms 19 Oct 2024 782nd grey0ut 444 105 435ms 11 Jan 2025 783rd croc54 443 146 10ms 15 Dec 2024 784th Yewzir 🇧🇪 442 171 12ms 26 Dec 2024 785th MyXoToD 🇩🇪 441 146 10ms 26 May 2025 786th PyryL 🇫🇮 440 147 10ms 1 Mar 2025 787th mbittner20 437 148 10ms 13 Oct 2024 787th YAJUE114514 437 148 10ms 12 Dec 2025 789th psaban 434 149 15ms 31 Jul 2025 789th TheZwierzLF 🇵🇱 434 149 11ms 24 Nov 2025 789th RodAlc24 🇪🇸 434 149 17ms 22 Feb 2026 792nd dokutan 433 130 289ms 17 Oct 2024 793rd Mabeloid 🇳🇴 433 133 538ms 2 Oct 2024 794th KatieLG 🇬🇧 433 183 2ms 2 Oct 2025 795th KatieLG 🇬🇧 431 108 6ms 13 Oct 2024 796th snoozingnewt 🇨🇦 431 111 34ms 2 Nov 2025 797th jameswmccarty 431 150 10ms 5 Oct 2024 797th yousefalizadeh 431 150 10ms 23 Oct 2024 797th feherd 431 150 11ms 31 Oct 2024 797th kadamkaustubh 431 150 10ms 8 Nov 2025 First Prev 721–800 of 913 Next Last