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 801st 5quiwyrm 858 52 304ms 4 Sep 2022 801st MeWhenI 🇻🇦 858 52 318ms 28 Jan 2023 801st Feniske 🇫🇷 858 52 317ms 7 Nov 2023 801st dcgjb 858 52 279ms 29 Jan 2024 801st JPRuskin 🇬🇧 858 52 314ms 7 Apr 2025 801st IISResetMe 858 52 325ms 7 Apr 2025 801st Ripick 858 52 315ms 1 Jun 2025 801st madex 🇩🇪 858 52 363ms 11 days ago 809th jared-hughes 858 72 2ms 6 Jul 2022 809th Steffan153 🇫🇮 858 72 2ms 3 Jan 2023 809th MeWhenI 🇻🇦 858 72 2ms 7 May 2023 809th ListeriaM 858 72 2ms 22 Aug 2023 809th larcherMTT 858 72 2ms 5 Oct 2024 809th snyderek 🇺🇸 858 72 2ms 19 Feb 2025 809th 5quiwyrm 858 72 2ms 29 Jun 2025 809th TeodorDyakov 🇧🇬 858 72 3ms 8 Jul 2025 809th xiaoyiming123 858 72 2ms 12 Jul 2025 818th Shanethegamer 🇺🇸 858 81 18ms 19 Dec 2023 818th emgordon154 858 81 20ms 29 Jul 2025 820th ovs-code 🇩🇪 857 83 57ms 1 Jul 2024 821st Liibe 857 97 477ms 25 Sep 2025 821st Schmitt-Very-Cool 857 97 434ms 26 Sep 2025 823rd frankgraziano 857 198 108ms 14 Oct 2025 824th typeswitch-dev 🇵🇹 856 75 5ms 22 Jul 2023 825th 386asm 🇺🇸 856 86 40ms 9 Apr 2023 825th DialFrost 🇸🇬 856 86 43ms 30 Dec 2025 827th nwellnhof 🇩🇪 856 111 301ms 4 May 2022 827th stefangimmillaro 856 111 310ms 26 Sep 2023 827th kkoenig 856 111 290ms 4 Jan 2024 830th Frowny 855 38 40ms 5 May 2022 830th stackofbears 855 38 42ms 14 Mar 2025 832nd DialFrost 🇸🇬 855 50 266ms 24 Oct 2023 833rd yeminghan2021 855 99 61ms 3 Feb 2025 834th ovs-code 🇩🇪 855 161 1,719ms 14 Sep 2025 835th Shanethegamer 🇺🇸 854 70 104ms 12 Dec 2022 835th Alessandro-Balconi 🇮🇹 854 70 103ms 26 Dec 2022 835th snoozingnewt 🇨🇦 854 70 210ms 22 Nov 2025 838th aditsu 854 77 2,622ms 23 Nov 2025 839th henrydukepickle 854 97 125ms 8 Jul 2025 840th eshilo-draper 853 91 358ms 4 Sep 2022 840th ericlangedijk 🇸🇮 853 91 369ms 23 May 2023 840th KatieLG 🇬🇧 853 91 377ms 30 Apr 2024 840th Mikey-Beep 🇬🇧 853 91 365ms 3 Sep 2024 844th MeWhenI 🇻🇦 853 92 467ms 10 Oct 2022 844th Betuaredead 853 92 480ms 5 Jan 2023 844th Yax42 🇫🇷 853 92 470ms 4 Oct 2025 847th Yewzir 🇧🇪 852 65 4ms 9 Oct 2023 847th MeWhenI 🇻🇦 852 65 4ms 10 Oct 2023 849th Shanethegamer 🇺🇸 852 83 1,252ms 4 May 2022 850th o0lit3 🇺🇸 851 54 8ms 22 Jun 2023 850th Natanaelel 🇸🇪 851 54 7ms 10 Feb 2025 852nd mtirado1 850 74 95ms 24 Dec 2022 852nd Betuaredead 850 74 95ms 6 Jan 2023 852nd KatieLG 🇬🇧 850 74 99ms 15 Jan 2023 852nd bwat2 850 74 90ms 31 Mar 2023 852nd stackotter 850 74 90ms 29 May 2023 852nd ovs-code 🇩🇪 850 74 91ms 17 Apr 2024 858th Shanethegamer 🇺🇸 850 99 24ms 27 Apr 2023 859th JayXon 🇺🇸 848 56 1,287ms 9 May 2022 860th the-zammers 847 68 165ms 2 Oct 2023 861st dokutan 847 82 21ms 1 Jul 2024 862nd lynn 847 96 29ms 11 Jul 2023 863rd jared-hughes 847 100 58ms 20 Jul 2022 863rd ZakkkkAttackkkk 🇵🇭 847 100 64ms 10 Aug 2022 863rd Walter225 847 100 62ms 25 Jul 2023 866th MeWhenI 🇻🇦 846 26 160ms 25 Aug 2022 866th AlephSquirrel 846 26 157ms 6 Jan 2023 866th ovs-code 🇩🇪 846 26 367ms 5 May 2024 866th saito-ta 🇯🇵 846 26 154ms 12 Dec 2024 870th shinh 846 52 43ms 29 Jun 2022 870th MeWhenI 🇻🇦 846 52 67ms 25 Jul 2023 872nd Natanaelel 🇸🇪 846 57 459ms 17 Jan 2024 872nd Kacarott 🇦🇺 846 57 402ms 10 Sep 2024 872nd albanian-laundromat 846 57 526ms 7 Oct 2025 875th randolchance 846 63 11ms 8 Jan 2023 875th CatsAreFluffy 846 63 14ms 18 Feb 2023 875th amiralitaheri 846 63 11ms 23 Feb 2023 875th RuyiLi 846 63 11ms 1 Apr 2023 875th TaserTheFox 🇺🇸 846 63 11ms 25 May 2023 875th pfysches-boop 846 63 11ms 6 Aug 2023 First Prev 801–880 of 3,621 Next Last