The Gray Code Decoder and Gray Code Encoder holes will go live in approximately 5 days. Why not try and solve them ahead of time?
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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 800th emplv 🇱🇻 689 89 135ms 28 Mar 2025 800th ovs-code 🇩🇪 689 89 139ms 17 Apr 2025 803rd snoozingnewt 🇨🇦 688 119 101ms 5 Dec 2025 804th janbehrens 🇩🇪 688 155 432ms 23 Jun 2023 805th retrohun 687 75 2ms 9 Nov 2022 806th Yewzir 🇧🇪 687 112 480ms 1 Dec 2023 806th michelebastione 🇮🇹 687 112 419ms 20 Sep 2025 808th kkoenig 687 193 295ms 1 Jan 2024 808th rifatx 687 193 278ms 23 Jul 2024 810th denkyuu1 686 103 13ms 23 Feb 2026 811th cbrt-x 686 163 148ms 18 Sep 2023 812th luuumine 🇫🇷 686 176 146ms 24 Nov 2025 813th janbehrens 🇩🇪 685 85 299ms 23 Jun 2023 814th RockOfStone 685 126 2ms 30 Jul 2022 815th lynn 684 38 41ms 22 Jul 2022 816th m-tkach 🇺🇦 684 90 455ms 21 Jan 2024 817th 0e4ef622 683 101 10ms 21 Jun 2022 817th bricknellj 683 101 9ms 22 Jun 2024 817th blaztoma 🇱🇹 683 101 10ms 17 days ago 820th DialFrost 🇸🇬 682 90 131ms 3 Nov 2024 821st IlkkaTakala 682 162 63ms 1 Dec 2023 822nd error256 680 66 37ms 8 May 2025 823rd MeWhenI 🇻🇦 680 81 330ms 28 Jan 2023 824th a6166231 🇨🇳 680 104 12ms 29 May 2025 825th bumchen 678 163 58ms 6 Apr 2023 826th DialFrost 🇸🇬 677 84 5ms 14 Aug 2024 827th bizy-coder 677 91 475ms 1 Apr 2024 827th MeWhenI 🇻🇦 677 91 436ms 24 May 2024 827th AlephSquirrel 677 91 469ms 3 Jul 2024 827th CaedenHarper 🇨🇦 677 91 437ms 30 Nov 2025 831st MeWhenI 🇻🇦 677 346 12ms 28 Aug 2023 832nd gnuvince 676 45 2ms 29 Jun 2025 833rd b10011 🇫🇮 676 102 9ms 14 Jan 2023 833rd bzijlema 🇳🇱 676 102 10ms 15 Oct 2024 833rd moustave 676 102 10ms 25 Jun 2025 833rd FoxInTheClouds 676 102 10ms 20 Feb 2026 833rd edsrzf 🇳🇿 676 102 11ms 21 days ago 833rd madex 🇩🇪 676 102 10ms 10 days ago 833rd firegene 🇮🇪 676 102 10ms 2 days ago 840th HumanoidCPU 676 136 1ms 4 Mar 2025 841st Shanethegamer 🇺🇸 675 99 87ms 12 Dec 2022 842nd fabianrieder 675 114 429ms 6 Apr 2023 843rd prestosilver 🇺🇸 674 164 65ms 2 days ago 844th fantaize 674 179 148ms 15 days ago 845th jacobly0 🇺🇸 674 193 41ms 18 Sep 2025 846th MeWhenI 🇻🇦 674 199 25ms 2 Oct 2024 847th alexsave 673 105 10ms 8 Nov 2024 847th acollett89 673 105 10ms 1 Aug 2025 847th LordSir101 673 105 11ms 16 Aug 2025 850th MeWhenI 🇻🇦 672 246 8ms 30 Nov 2023 851st violeta-desantis 671 137 2ms 27 Sep 2023 852nd inventshah 670 92 474ms 21 Jan 2024 853rd janbehrens 🇩🇪 670 103 9ms 23 Jun 2023 853rd orthoplex 🇨🇽 670 103 10ms 25 Nov 2023 853rd abc7-12 670 103 10ms 26 Jun 2024 853rd Lv0Sys 🇵🇱 670 103 11ms 6 Dec 2025 853rd FortuiteMan 🇫🇷 670 103 10ms 18 Dec 2025 853rd Emutis 🇱🇹 670 103 10ms 17 days ago 859th bac0id 670 159 424ms 26 Sep 2023 860th msbranicky 670 165 56ms 20 Aug 2023 860th Herbert00709 🇵🇱 670 165 63ms 10 days ago 862nd stefangimmillaro 669 67 40ms 26 Dec 2024 863rd janbehrens 🇩🇪 669 115 485ms 23 Jun 2023 864th SirBogman 🇺🇸 668 59 32ms 8 Sep 2022 865th SirBogman 🇺🇸 667 39 41ms 4 Oct 2022 866th zakariamouhid 667 106 11ms 14 May 2023 867th Yewzir 🇧🇪 666 87 1,002ms 15 Nov 2025 868th SirBogman 🇺🇸 666 150 38ms 4 Dec 2022 869th varhammer 666 152 7ms 7 Nov 2024 870th Schmitt-Very-Cool 666 160 471ms 30 Sep 2025 871st swbbl 663 83 305ms 5 Feb 2022 871st Feniske 🇫🇷 663 83 315ms 8 Aug 2022 873rd VictorFordham 663 104 10ms 20 Feb 2023 873rd Alex-x90 🇺🇸 663 104 10ms 3 Aug 2023 873rd mathisfun271 663 104 9ms 5 Feb 2024 873rd EnTerr 663 104 10ms 8 Sep 2024 873rd KasperKivimaeki 🇫🇮 663 104 10ms 11 Jul 2025 878th roavin 663 116 398ms 23 Jun 2022 878th hamhub7 663 116 397ms 9 Aug 2022 878th bac0id 663 116 397ms 22 Sep 2023 First Prev 801–880 of 1,610 Next Last