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?
Collatz 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 480th GrayJoKing 🇦🇺 895 69 7ms 12 Sep 2022 480th btnlq 895 69 7ms 24 Sep 2022 480th trinityy-7 895 69 2ms 7 Aug 2025 484th SirBogman 🇺🇸 893 50 516ms 5 May 2022 484th nwellnhof 🇩🇪 893 50 504ms 3 Jun 2022 484th Lydxn 🇨🇦 893 50 431ms 15 Aug 2022 484th Steffan153 🇫🇮 893 50 485ms 9 Aug 2024 488th Steffan153 🇫🇮 893 67 112ms 18 Dec 2022 488th Lydxn 🇨🇦 893 67 122ms 4 Feb 2023 488th DialFrost 🇸🇬 893 67 101ms 17 Mar 2025 491st NickTheEASDude 🇺🇸 893 76 6ms 7 May 2024 491st edsrzf 🇳🇿 893 76 6ms 23 Dec 2025 491st Shanethegamer 🇺🇸 893 76 5ms 23 Dec 2025 491st jared-hughes 893 76 5ms 24 Dec 2025 491st Waffle3z 893 76 5ms 26 Dec 2025 491st Blendi-Goose 893 76 5ms 6 Feb 2026 491st kTheLemon 893 76 5ms 20 days ago 498th MichalMarsalek 🇨🇿 893 87 379ms 5 May 2022 498th Kloppermand 🇩🇰 893 87 350ms 7 Oct 2022 498th bwat2 893 87 367ms 6 Apr 2023 498th bpharaldsson 893 87 425ms 9 Feb 2026 502nd GrayJoKing 🇦🇺 893 91 30ms 19 Jan 2023 503rd Lydxn 🇨🇦 892 72 353ms 16 Jul 2023 504th edsrzf 🇳🇿 892 78 12ms 26 Oct 2024 505th Ripick 891 73 122ms 8 May 2023 506th edsrzf 🇳🇿 891 78 17ms 16 Aug 2025 507th dokutan 891 88 425ms 15 Feb 2026 508th oeb25 891 93 127ms 16 May 2022 508th snobee 🇨🇦 891 93 128ms 8 Dec 2022 508th logvp 891 93 130ms 2 Jan 2024 508th smartiel 891 93 131ms 12 Aug 2024 508th trist224 🇫🇷 891 93 131ms 12 Aug 2024 508th nullie 891 93 128ms 19 Dec 2024 508th lolgeny 891 93 138ms 22 Feb 2025 515th GolfingSuccess 🇬🇷 891 95 60ms 5 May 2022 515th Alex-x90 🇺🇸 891 95 65ms 4 Dec 2022 515th Mandrzejy 🇵🇱 891 95 60ms 22 Mar 2024 518th m-tkach 🇺🇦 891 117 25ms 7 May 2022 518th Lydxn 🇨🇦 891 117 26ms 7 May 2022 520th p-zubieta 890 48 299ms 6 Mar 2024 521st Steffan153 🇫🇮 890 80 28ms 15 Nov 2022 521st error256 890 80 117ms 8 Apr 2025 523rd KatieLG 🇬🇧 889 60 11ms 4 May 2022 523rd ScottHamper 889 60 12ms 5 May 2022 523rd Re-Adventures 🇮🇳 889 60 11ms 5 May 2022 523rd 0x24a537r9 889 60 13ms 29 Jul 2022 523rd stefangabos 🇷🇴 889 60 11ms 19 Aug 2022 523rd eranws 889 60 12ms 10 Sep 2022 523rd GeorgeStechman 🇬🇧 889 60 12ms 26 Sep 2022 523rd BloodStormKnight 889 60 11ms 15 Oct 2022 523rd dzshn 889 60 11ms 3 Dec 2022 523rd biocommando 🇫🇮 889 60 10ms 20 Dec 2022 523rd Betuaredead 889 60 12ms 5 Jan 2023 523rd piano-miles 889 60 14ms 16 Jan 2023 523rd Yewzir 🇧🇪 889 60 11ms 12 Feb 2023 523rd shellbertt 🇨🇦 889 60 12ms 26 Feb 2023 523rd zakariamouhid 889 60 10ms 20 May 2023 523rd raphaelimahorn 889 60 11ms 23 Aug 2023 523rd jbt 889 60 13ms 25 Dec 2023 523rd olleicua 🇺🇸 889 60 11ms 15 Feb 2024 523rd HumanoidCPU 889 60 15ms 3 May 2024 523rd dokutan 889 60 14ms 13 Aug 2024 523rd LostSyntax21 🇬🇧 889 60 10ms 10 Sep 2024 523rd xyangst 889 60 11ms 28 Sep 2024 523rd a6166231 🇨🇳 889 60 11ms 15 May 2025 523rd SebassNoob 889 60 12ms 5 Aug 2025 523rd levinwinter 889 60 11ms 22 Oct 2025 523rd Cube14yt 889 60 12ms 16 Nov 2025 523rd gigaprofisi 🇺🇸 889 60 11ms 17 Nov 2025 523rd amazingalek 🇳🇴 889 60 11ms 20 Dec 2025 523rd shandriy 889 60 13ms 23 Jan 2026 523rd spidunno 889 60 11ms 17 Feb 2026 553rd JayXon 🇺🇸 889 74 2,528ms 14 Nov 2024 554th Lydxn 🇨🇦 888 107 284ms 6 May 2022 554th CaedenHarper 🇨🇦 888 107 299ms 5 Oct 2025 556th canissimia 🇦🇶 888 204 16ms 25 Nov 2023 557th Shanethegamer 🇺🇸 887 61 4ms 31 Oct 2022 557th MeWhenI 🇻🇦 887 61 4ms 4 Nov 2022 559th P-Quentin 🇫🇷 887 63 20ms 3 Aug 2022 559th kaptsanovb 887 63 25ms 20 Apr 2023 First Prev 481–560 of 3,621 Next Last