The Gray Code Decoder and Gray Code Encoder holes will go live in approximately 6 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 641st anter69 🇭🇺 748 60 38ms 12 Feb 2024 642nd iczelia 🇩🇪 748 123 1ms 24 Sep 2025 643rd Shanethegamer 🇺🇸 748 251 1,452ms 25 Jan 2025 644th edsrzf 🇳🇿 747 78 386ms 11 Oct 2025 645th nwellnhof 🇩🇪 747 88 31ms 12 Jul 2022 646th emplv 🇱🇻 747 101 111ms 6 Dec 2022 647th bac0id 747 148 61ms 3 Jul 2024 648th emgordon154 746 128 553ms 3 Jun 2025 649th tobeannouncd 745 150 144ms 20 Dec 2024 650th dylanarmstrong 744 95 11ms 12 Jan 2024 650th junkondo-jp 744 95 10ms 2 Jun 2024 652nd chlorobenzene12 744 116 2ms 26 Dec 2022 653rd KrausRaus 🇺🇸 744 117 2ms 15 Oct 2023 654th Frowny 743 53 32ms 11 Jan 2022 655th CaedenHarper 🇨🇦 743 78 823ms 30 Sep 2025 656th stackofbears 742 41 2ms 20 Feb 2022 656th akamayu-ouo 🇹🇼 742 41 2ms 8 Jul 2024 656th AlephSquirrel 742 41 2ms 8 Nov 2025 659th HumanoidCPU 742 83 426ms 2 Mar 2025 660th QuincyNash 🇺🇸 742 93 16ms 21 Jan 2022 661st BlankSpruce 742 149 57ms 16 Jan 2022 662nd djeedjay 🇳🇱 741 124 1ms 16 Sep 2022 663rd MeWhenI 🇻🇦 741 129 449ms 4 Aug 2023 664th HumanoidCPU 741 179 279ms 3 Mar 2025 665th BREMAUCY 🇫🇷 741 316 13ms 15 Dec 2025 666th primo-ppcg 🇹🇭 740 144 419ms 4 Apr 2022 666th Lydxn 🇨🇦 740 144 435ms 5 Apr 2022 666th rotary-o 🇯🇵 740 144 457ms 5 May 2023 666th Jacob385 740 144 547ms 28 Oct 2025 670th stefangimmillaro 739 102 107ms 19 Oct 2022 671st MeWhenI 🇻🇦 739 123 369ms 30 Jan 2023 672nd Shanethegamer 🇺🇸 737 111 106ms 4 Dec 2025 673rd emplv 🇱🇻 737 182 25ms 31 Oct 2022 674th ovs-code 🇩🇪 736 70 2ms 8 Nov 2022 675th 4hg 🇺🇸 736 79 1,316ms 8 Dec 2022 675th anter69 🇭🇺 736 79 1,340ms 19 Feb 2023 675th emgordon154 736 79 1,321ms 25 Nov 2024 675th Shanethegamer 🇺🇸 736 79 1,255ms 9 Apr 2025 679th BambooleanLogic 🇸🇪 736 96 11ms 20 Aug 2022 679th vroup 🇩🇰 736 96 11ms 2 Oct 2022 679th Ultra814 736 96 10ms 17 Aug 2025 682nd jupj 🇫🇮 736 125 2ms 31 Aug 2022 683rd weliveinhell 🇭🇹 736 180 300ms 4 Oct 2023 683rd emgordon154 736 180 281ms 20 Feb 2025 685th SirBogman 🇺🇸 735 61 37ms 21 May 2022 685th Shanethegamer 🇺🇸 735 61 37ms 27 May 2022 685th canissimia 🇦🇶 735 61 39ms 18 Jul 2022 688th dokutan 734 79 994ms 8 Sep 2025 689th xnor-gate 734 94 16ms 30 Jul 2024 690th madex 🇩🇪 734 96 2,855ms 4 days ago 691st billings7 🇬🇧 733 105 428ms 12 Nov 2023 691st MiffOttah 733 105 422ms 28 Nov 2024 693rd retrohun 732 151 53ms 30 Dec 2022 693rd annaproxy 732 151 60ms 5 Jan 2023 695th JRaspass 🇬🇧 732 181 295ms 23 Sep 2022 696th SirBogman 🇺🇸 732 320 14ms 21 May 2022 697th Steffan153 🇫🇮 731 57 3ms 6 Jan 2023 697th Natanaelel 🇸🇪 731 57 4ms 13 May 2023 699th bac0id 730 126 1ms 3 Jul 2024 700th Yewzir 🇧🇪 730 137 35ms 28 Nov 2023 701st yzhs 🇩🇪 730 153 146ms 25 Jun 2023 702nd iczelia 🇩🇪 729 97 10ms 26 Sep 2025 702nd johnkiernander 729 97 11ms 14 Dec 2025 704th MeWhenI 🇻🇦 729 160 41ms 4 Sep 2024 705th chunes3 🇺🇸 727 100 70ms 15 Sep 2023 705th Natanaelel 🇸🇪 727 100 70ms 8 Dec 2023 707th jared-hughes 727 152 461ms 24 Jun 2022 707th Betuaredead 727 152 460ms 7 Jan 2023 709th GeneralTwi 726 95 10ms 2 May 2022 710th ericlangedijk 🇸🇮 726 106 421ms 19 Mar 2022 711th KenanSi 725 42 2ms 24 Feb 2022 711th Natanaelel 🇸🇪 725 42 2ms 21 Jun 2022 711th GolfingSuccess 🇬🇷 725 42 2ms 31 Dec 2022 714th JunkIce 725 85 427ms 3 Dec 2024 715th Shanethegamer 🇺🇸 724 138 38ms 6 Sep 2022 716th Shanethegamer 🇺🇸 724 161 41ms 13 Feb 2025 717th mlugg 724 203 1,617ms 10 Aug 2024 718th Natanaelel 🇸🇪 723 62 37ms 18 May 2025 719th AlephSquirrel 722 36 45ms 29 Dec 2022 720th dokutan 722 153 81ms 8 Nov 2025 First Prev 641–720 of 1,610 Next Last