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?
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 320th JayXon 🇺🇸 912 86 481ms 15 May 2023 320th Steffan153 🇫🇮 912 86 460ms 16 May 2023 320th Lydxn 🇨🇦 912 86 456ms 16 May 2023 320th GrayJoKing 🇦🇺 912 86 461ms 11 Aug 2023 320th sean-niemann 🇺🇸 912 86 468ms 11 Jul 2024 326th Bubbler-4 911 33 2,528ms 6 May 2022 326th rak1507 🇬🇧 911 33 108ms 8 May 2022 326th ngn 🇧🇬 911 33 25ms 11 May 2022 326th zacjl 911 33 32ms 3 Jun 2025 326th GrayJoKing 🇦🇺 911 33 13ms 4 Jun 2025 326th HPWiz 🇳🇿 911 33 9ms 16 Nov 2025 332nd Lydxn 🇨🇦 911 70 148ms 7 May 2022 332nd JayXon 🇺🇸 911 70 143ms 7 May 2022 334th Steffan153 🇫🇮 911 71 124ms 14 Oct 2022 334th Shanethegamer 🇺🇸 911 71 125ms 15 Oct 2022 334th stefangimmillaro 911 71 114ms 16 Oct 2022 334th MeWhenI 🇻🇦 911 71 118ms 16 Oct 2022 338th andersk 🇺🇸 911 91 139ms 25 Oct 2022 338th Super-Pizza 🇨🇦 911 91 128ms 4 Dec 2022 338th klixel 🇨🇦 911 91 126ms 20 May 2023 338th lynn 911 91 128ms 6 Jul 2024 338th edsrzf 🇳🇿 911 91 126ms 29 Nov 2024 338th DialFrost 🇸🇬 911 91 139ms 7 Apr 2025 338th elgan65536 🇺🇸 911 91 122ms 10 Feb 2026 338th fantaize 911 91 129ms 17 days ago 346th tailorspy 910 93 55ms 27 May 2024 346th sean-niemann 🇺🇸 910 93 60ms 9 Jun 2025 346th KasperKivimaeki 🇫🇮 910 93 63ms 26 Oct 2025 349th Lydxn 🇨🇦 909 47 257ms 5 May 2022 350th JayXon 🇺🇸 909 53 411ms 17 Aug 2024 351st Lydxn 🇨🇦 909 81 39ms 1 Apr 2023 352nd Shanethegamer 🇺🇸 908 61 4ms 9 Oct 2023 353rd nai62 908 68 7ms 27 Aug 2022 354th Steffan153 🇫🇮 908 73 68ms 26 Feb 2026 355th ovs-code 🇩🇪 908 75 67ms 12 Sep 2024 355th Kacarott 🇦🇺 908 75 62ms 13 Sep 2024 357th sean-niemann 🇺🇸 907 54 138ms 6 Aug 2024 357th Steffan153 🇫🇮 907 54 134ms 6 Aug 2024 357th lukegustafson 🇺🇸 907 54 139ms 7 Aug 2024 357th pardouin 🇫🇷 907 54 145ms 8 Aug 2024 357th Lydxn 🇨🇦 907 54 164ms 9 Aug 2024 362nd lynn 907 78 1,231ms 5 May 2022 363rd sean-niemann 🇺🇸 906 66 112ms 29 May 2025 364th GrayJoKing 🇦🇺 905 71 321ms 10 Aug 2023 365th sean-niemann 🇺🇸 905 75 5ms 23 Dec 2025 365th Steffan153 🇫🇮 905 75 5ms 11 Feb 2026 367th primo-ppcg 🇹🇭 905 93 30ms 7 May 2022 367th AlephSquirrel 905 93 26ms 21 Jan 2023 367th kg583 🇺🇸 905 93 29ms 26 Dec 2024 367th CLOStrophobic 🇮🇹 905 93 30ms 17 Jan 2025 367th edsrzf 🇳🇿 905 93 30ms 3 Jul 2025 372nd JayXon 🇺🇸 905 105 291ms 4 Oct 2025 373rd KrausRaus 🇺🇸 904 59 15ms 4 May 2022 373rd voytxt 🇨🇿 904 59 10ms 4 May 2022 373rd KingSkyrock 🇺🇸 904 59 12ms 18 May 2022 373rd ZakkkkAttackkkk 🇵🇭 904 59 10ms 14 Jul 2022 373rd aksyristos 904 59 11ms 28 Oct 2022 373rd nstearns96 🇬🇧 904 59 11ms 28 Nov 2022 373rd janbehrens 🇩🇪 904 59 14ms 17 May 2023 373rd Shanethegamer 🇺🇸 904 59 11ms 25 May 2023 373rd Maznek 904 59 11ms 26 Jun 2023 373rd SpiritAxolotl 🇺🇸 904 59 11ms 20 Mar 2024 373rd Andrey-Plotnikov 904 59 11ms 19 May 2024 373rd emgordon154 904 59 13ms 5 Aug 2024 373rd duckyluuk 🇳🇱 904 59 12ms 3 Oct 2024 373rd lifthrasiir 🇰🇷 904 59 11ms 23 Nov 2024 373rd fuzzylojik-golf 🇺🇸 904 59 11ms 1 Jun 2025 373rd acollett89 904 59 12ms 17 Jun 2025 373rd iczelia 🇩🇪 904 59 12ms 23 Sep 2025 373rd Yax42 🇫🇷 904 59 10ms 20 Jan 2026 373rd Protothor 904 59 11ms 37 hours ago 392nd edsrzf 🇳🇿 903 72 128ms 3 Jul 2025 393rd Shanethegamer 🇺🇸 903 77 14ms 15 May 2023 394th marshallward 🇺🇸 903 83 40ms 10 May 2022 395th krcs 🇵🇱 903 86 381ms 10 May 2022 395th billings7 🇬🇧 903 86 384ms 15 May 2022 395th revlayle 🇺🇸 903 86 379ms 7 Dec 2022 395th albanian-laundromat 903 86 430ms 30 Sep 2025 399th m-tkach 🇺🇦 903 90 31ms 7 Dec 2023 400th piano-miles 903 92 411ms 24 Feb 2026 First Prev 321–400 of 3,621 Next Last