The Gray Code Decoder and Gray Code Encoder holes will go live in approximately 26 hours. Why not try and solve them ahead of time?
Card Number Validation in all languages in bytes. 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 Bytes Time Submitted 721st denkyuu1 544 88 35ms 3 days ago 722nd PyryL 🇫🇮 543 147 10ms 1 Mar 2025 723rd eranws 542 119 10ms 23 Dec 2024 723rd ComradeSquirrel 542 119 10ms 19 hours ago 725th dokutan 539 107 956ms 18 days ago 726th dokutan 539 131 2ms 10 Feb 2026 727th Sciman101 539 147 2ms 26 Mar 2025 728th mbittner20 539 148 10ms 13 Oct 2024 728th YAJUE114514 539 148 10ms 12 Dec 2025 730th psaban 535 149 15ms 31 Jul 2025 730th TheZwierzLF 🇵🇱 535 149 11ms 24 Nov 2025 730th RodAlc24 🇪🇸 535 149 17ms 22 Feb 2026 733rd msbranicky 534 175 156ms 13 Dec 2024 734th JRaspass 🇬🇧 533 74 3ms 6 days ago 735th deancureton 533 121 11ms 30 Dec 2024 736th FlorianCassayre 🇫🇷 532 150 18ms 1 Oct 2024 736th jameswmccarty 532 150 10ms 5 Oct 2024 736th yousefalizadeh 532 150 10ms 23 Oct 2024 736th feherd 532 150 11ms 31 Oct 2024 736th kadamkaustubh 532 150 10ms 8 Nov 2025 741st msbranicky 530 126 2,655ms 9 Jan 2025 742nd Protothor 528 122 11ms 20 days ago 743rd adamnielson42 🇺🇸 525 152 10ms 6 Oct 2024 743rd voidgloom 525 152 10ms 22 Oct 2024 743rd omero-san 525 152 10ms 22 Sep 2025 743rd brochmann 🇸🇪 525 152 10ms 12 Oct 2025 747th Macweese 525 178 405ms 3 Aug 2025 748th isaiah0311 🇺🇸 523 135 2ms 9 Feb 2026 749th galloj 🇨🇿 522 112 19ms 4 Oct 2024 750th TheZwierzLF 🇵🇱 522 127 507ms 12 Dec 2025 751st xyangst 521 153 11ms 1 Oct 2024 751st denisfouchard 521 153 10ms 21 Aug 2025 753rd snoozingnewt 🇨🇦 520 213 138ms 2 Nov 2025 754th bac0id 519 180 388ms 9 Jan 2025 755th osNiko 🇧🇷 518 154 9ms 21 Aug 2025 756th sidok 516 109 248ms 13 Nov 2024 757th robin-scragg 515 155 11ms 21 Aug 2025 757th celiendonze 🇨🇭 515 155 10ms 17 Oct 2025 757th aksyristos 515 155 10ms 21 days ago 760th Andrey2001 514 129 525ms 1 Feb 2026 761st dokutan 514 143 210ms 19 Oct 2024 762nd nephila-nacrea 🇬🇧 512 77 4ms 2 Oct 2024 763rd travisdoesmath 511 156 10ms 7 Sep 2025 763rd Shotokhan 511 156 10ms 21 Sep 2025 765th KatieLG 🇬🇧 510 140 361ms 1 Oct 2024 766th yoshykai 510 183 374ms 12 Apr 2025 767th Chinay-Domitrix 🇺🇸 509 131 2,759ms 30 Mar 2025 768th KatieLG 🇬🇧 509 146 9ms 2 Oct 2024 769th lhulinsky 508 157 10ms 21 Oct 2024 770th dokutan 507 126 156ms 22 Jun 2025 771st ellis-rix 505 158 10ms 9 Dec 2024 772nd osNiko 🇧🇷 503 72 51ms 11 Jan 2026 773rd msbranicky 503 138 3ms 3 Oct 2024 774th snoozingnewt 🇨🇦 503 142 436ms 2 Nov 2025 775th webmiche 502 159 11ms 3 Nov 2025 776th jlangvand 501 141 1ms 15 Oct 2024 776th HumanoidCPU 501 141 1ms 7 Mar 2025 778th blaztoma 🇱🇹 500 154 119ms 28 Nov 2025 779th Mabeloid 🇳🇴 499 133 538ms 2 Oct 2024 780th MeWhenI 🇻🇦 499 149 56ms 4 Oct 2024 781st CheeseCake628 🇳🇴 498 160 104ms 5 Nov 2024 782nd pres-abhisheksinha 495 161 10ms 8 Oct 2024 783rd CarterStroik 493 161 2ms 19 Nov 2025 784th owen-c-parker 🇺🇸 492 131 11ms 1 Oct 2024 785th HumanoidCPU 492 145 480ms 5 Oct 2024 786th ibixina 492 162 11ms 13 Oct 2024 786th TheAtrossian 492 162 11ms 5 Jan 2025 788th h-hh-hhh 🇺🇦 491 177 70ms 2 Nov 2024 789th snoozingnewt 🇨🇦 491 249 26ms 2 Nov 2025 790th snoozingnewt 🇨🇦 490 150 219ms 2 Nov 2025 791st JunkIce 488 136 510ms 3 Dec 2024 792nd snoozingnewt 🇨🇦 486 117 1,338ms 2 Nov 2025 793rd Vaekor 483 165 11ms 15 Dec 2024 794th mitzal 483 180 70ms 9 Feb 2025 795th snoozingnewt 🇨🇦 482 173 377ms 2 Nov 2025 796th h-hh-hhh 🇺🇦 480 147 1ms 2 Nov 2024 797th denkyuu1 477 118 287ms 3 days ago 798th MiffOttah 476 150 478ms 6 Oct 2024 798th mwarvik 🇳🇴 476 150 431ms 1 Jan 2026 800th alphafalfa 472 92 2ms 8 Nov 2024 First Prev 721–800 of 919 Next Last