The Gray Code Decoder and Gray Code Encoder holes will go live in approximately 3 days. Why not try and solve them ahead of time?
Roman to Arabic 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 801st madex 🇩🇪 576 160 190ms 14 days ago 802nd PaulTaykalo 576 170 157ms 24 Sep 2020 803rd annaproxy 575 125 20ms 9 May 2022 803rd commandz0 🇺🇸 575 125 21ms 21 May 2023 803rd davecame 575 125 23ms 14 Sep 2023 806th madex 🇩🇪 575 142 3ms 14 days ago 807th frankgraziano 575 173 22ms 24 Feb 2026 808th CaedenHarper 🇨🇦 574 136 8ms 22 Aug 2025 809th CaedenHarper 🇨🇦 573 124 3,551ms 18 Aug 2025 810th alexsave 573 132 21ms 14 Jan 2026 811th DanielRHolland 573 194 359ms 12 Nov 2020 812th MeWhenI 🇻🇦 572 77 6ms 16 Apr 2023 812th janbehrens 🇩🇪 572 77 6ms 18 May 2023 814th Indivicivet 571 126 20ms 26 Oct 2021 814th vishwathg 571 126 26ms 2 Feb 2023 816th DaCuteRaccoon 569 133 14ms 8 Dec 2022 817th Yewzir 🇧🇪 569 139 143ms 9 Jun 2024 818th MeWhenI 🇻🇦 569 168 1,438ms 16 Jun 2023 819th commandz0 🇺🇸 567 114 537ms 1 Sep 2025 820th CaedenHarper 🇨🇦 567 144 4ms 16 Nov 2025 821st marcin7Cd 566 127 20ms 28 Sep 2019 822nd Sciman101 566 158 6ms 16 May 2023 823rd CaedenHarper 🇨🇦 566 173 773ms 22 Aug 2025 824th annaproxy 564 197 327ms 23 Feb 2023 825th Natanaelel 🇸🇪 563 145 4ms 16 Feb 2026 826th daedals 562 128 19ms 31 May 2019 826th mathb0y512 562 128 21ms 11 Jan 2024 826th mathisfun271 562 128 44ms 13 Feb 2024 826th moustave 562 128 19ms 7 Apr 2025 830th janbehrens 🇩🇪 561 105 2,700ms 18 May 2023 831st melven 561 215 42ms 16 Oct 2025 832nd GrayJoKing 🇦🇺 560 61 41ms 23 Oct 2020 833rd HumanoidCPU 560 135 16ms 8 Jun 2024 834th Jacob385 558 181 388ms 28 Oct 2025 835th CaedenHarper 🇨🇦 557 117 164ms 17 Aug 2025 836th jared-hughes 557 129 21ms 2 Oct 2021 836th ahmetdemirag 🇨🇾 557 129 21ms 4 Jul 2024 838th BambooleanLogic 🇸🇪 556 136 18ms 3 Nov 2022 839th djeedjay 🇳🇱 555 147 3ms 6 Sep 2021 840th CaedenHarper 🇨🇦 555 181 71ms 16 Nov 2025 841st JunkIce 553 117 462ms 3 Dec 2024 842nd Bmrl7 553 130 21ms 7 Mar 2024 843rd emgordon154 552 221 110ms 10 Jun 2025 844th lynn 551 62 42ms 24 Oct 2021 845th Anonymousellama21 549 131 22ms 16 May 2024 846th uttumuttu 🇫🇮 548 138 20ms 5 Jan 2022 846th KaleChips22 548 138 13ms 3 Aug 2025 848th joll05 🇸🇪 545 132 22ms 20 Aug 2020 848th SnowballSH 545 132 28ms 3 Feb 2021 848th jeff-at-tamer-dot-codes 🇺🇸 545 132 23ms 25 Mar 2024 851st ShiraJoseph 🇺🇸 544 139 21ms 25 Jun 2023 852nd kkoenig 544 228 317ms 13 Sep 2024 853rd UnderKoen 🇳🇱 542 225 129ms 8 Jul 2024 854th tkwa 541 133 21ms 4 Dec 2018 854th fourth-bit 541 133 42ms 13 Jul 2023 856th mckymsh 540 140 15ms 1 Mar 2022 857th relet 537 134 21ms 8 Aug 2018 858th phdphil 536 93 179ms 22 Apr 2018 859th bstrautin 535 109 3,906ms 26 Jul 2020 860th jared-hughes 533 64 43ms 17 Apr 2022 861st suwat513 533 135 43ms 15 Sep 2022 862nd kevinmchung 529 136 28ms 3 Apr 2018 862nd jarekwg 529 136 19ms 2 Oct 2020 862nd OCNeve 529 136 20ms 18 Jun 2024 862nd minhtrancccp 529 136 21ms 25 Nov 2024 866th xkacer 🇨🇿 529 143 19ms 25 Jan 2021 866th trinityy-7 529 143 15ms 17 Mar 2024 868th elgan65536 🇺🇸 529 214 204ms 27 Mar 2024 869th neihousaigaai 525 137 21ms 6 Oct 2024 870th emgordon154 525 144 19ms 9 Dec 2021 871st adamnielson42 🇺🇸 522 77 36ms 7 Dec 2023 872nd hiddicop 🇸🇪 522 92 55ms 1 Feb 2021 872nd jared-hughes 522 92 47ms 20 Sep 2022 874th Kibble 522 145 13ms 4 Oct 2020 874th IchBinMichMarkus 522 145 15ms 11 Jul 2023 876th CaedenHarper 🇨🇦 522 373 1,517ms 22 Aug 2025 877th IISResetMe 521 112 788ms 8 Mar 2024 877th CaedenHarper 🇨🇦 521 112 329ms 22 Aug 2025 879th zbreit 🇺🇸 521 138 24ms 6 Aug 2020 879th rschwa6308 🇺🇸 521 138 26ms 6 Aug 2020 First Prev 801–880 of 1,509 Next Last