The Gray Code Decoder and Gray Code Encoder holes will go live in approximately 2 hours. 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 799th Natanaelel 🇸🇪 858 41 434ms 4 May 2022 802nd 5quiwyrm 858 52 304ms 4 Sep 2022 802nd MeWhenI 🇻🇦 858 52 318ms 28 Jan 2023 802nd Feniske 🇫🇷 858 52 317ms 7 Nov 2023 802nd dcgjb 858 52 279ms 29 Jan 2024 802nd JPRuskin 🇬🇧 858 52 314ms 7 Apr 2025 802nd IISResetMe 858 52 325ms 7 Apr 2025 802nd Ripick 858 52 315ms 1 Jun 2025 802nd madex 🇩🇪 858 52 363ms 15 days ago 810th jared-hughes 858 72 2ms 6 Jul 2022 810th Steffan153 🇫🇮 858 72 2ms 3 Jan 2023 810th MeWhenI 🇻🇦 858 72 2ms 7 May 2023 810th ListeriaM 858 72 2ms 22 Aug 2023 810th larcherMTT 858 72 2ms 5 Oct 2024 810th snyderek 🇺🇸 858 72 2ms 19 Feb 2025 810th 5quiwyrm 858 72 2ms 29 Jun 2025 810th TeodorDyakov 🇧🇬 858 72 3ms 8 Jul 2025 810th xiaoyiming123 858 72 2ms 12 Jul 2025 819th Shanethegamer 🇺🇸 858 81 18ms 19 Dec 2023 819th emgordon154 858 81 20ms 29 Jul 2025 821st ovs-code 🇩🇪 857 83 57ms 1 Jul 2024 822nd Liibe 857 97 477ms 25 Sep 2025 822nd Schmitt-Very-Cool 857 97 434ms 26 Sep 2025 824th frankgraziano 857 198 108ms 14 Oct 2025 825th typeswitch-dev 🇵🇹 856 75 5ms 22 Jul 2023 826th 386asm 🇺🇸 856 86 40ms 9 Apr 2023 826th DialFrost 🇸🇬 856 86 43ms 30 Dec 2025 828th nwellnhof 🇩🇪 856 111 301ms 4 May 2022 828th stefangimmillaro 856 111 310ms 26 Sep 2023 828th kkoenig 856 111 290ms 4 Jan 2024 831st Frowny 855 38 40ms 5 May 2022 831st stackofbears 855 38 42ms 14 Mar 2025 833rd DialFrost 🇸🇬 855 50 266ms 24 Oct 2023 834th Shanethegamer 🇺🇸 855 70 104ms 12 Dec 2022 834th Alessandro-Balconi 🇮🇹 855 70 103ms 26 Dec 2022 834th snoozingnewt 🇨🇦 855 70 210ms 22 Nov 2025 837th yeminghan2021 855 99 58ms 3 Feb 2025 838th ovs-code 🇩🇪 855 161 1,719ms 14 Sep 2025 839th aditsu 854 77 2,622ms 23 Nov 2025 840th henrydukepickle 854 97 125ms 8 Jul 2025 841st eshilo-draper 853 91 358ms 4 Sep 2022 841st ericlangedijk 🇸🇮 853 91 369ms 23 May 2023 841st KatieLG 🇬🇧 853 91 377ms 30 Apr 2024 841st Mikey-Beep 🇬🇧 853 91 365ms 3 Sep 2024 845th MeWhenI 🇻🇦 853 92 467ms 10 Oct 2022 845th Betuaredead 853 92 480ms 5 Jan 2023 845th Yax42 🇫🇷 853 92 470ms 4 Oct 2025 848th Yewzir 🇧🇪 852 65 4ms 9 Oct 2023 848th MeWhenI 🇻🇦 852 65 4ms 10 Oct 2023 850th Shanethegamer 🇺🇸 852 83 1,252ms 4 May 2022 851st o0lit3 🇺🇸 851 54 7ms 22 Jun 2023 851st Natanaelel 🇸🇪 851 54 11ms 10 Feb 2025 853rd mtirado1 850 74 91ms 24 Dec 2022 853rd Betuaredead 850 74 95ms 6 Jan 2023 853rd KatieLG 🇬🇧 850 74 91ms 15 Jan 2023 853rd bwat2 850 74 88ms 31 Mar 2023 853rd stackotter 850 74 90ms 29 May 2023 853rd ovs-code 🇩🇪 850 74 85ms 17 Apr 2024 859th Shanethegamer 🇺🇸 850 99 24ms 27 Apr 2023 860th JayXon 🇺🇸 848 56 1,287ms 9 May 2022 861st the-zammers 847 68 165ms 2 Oct 2023 862nd dokutan 847 82 21ms 1 Jul 2024 863rd lynn 847 96 29ms 11 Jul 2023 864th jared-hughes 847 100 58ms 20 Jul 2022 864th ZakkkkAttackkkk 🇵🇭 847 100 64ms 10 Aug 2022 864th Walter225 847 100 62ms 25 Jul 2023 867th MeWhenI 🇻🇦 846 26 160ms 25 Aug 2022 867th AlephSquirrel 846 26 157ms 6 Jan 2023 867th ovs-code 🇩🇪 846 26 367ms 5 May 2024 867th saito-ta 🇯🇵 846 26 154ms 12 Dec 2024 871st shinh 846 52 43ms 29 Jun 2022 871st MeWhenI 🇻🇦 846 52 67ms 25 Jul 2023 873rd Natanaelel 🇸🇪 846 57 459ms 17 Jan 2024 873rd Kacarott 🇦🇺 846 57 402ms 10 Sep 2024 873rd albanian-laundromat 846 57 526ms 7 Oct 2025 876th randolchance 846 63 11ms 8 Jan 2023 876th CatsAreFluffy 846 63 13ms 18 Feb 2023 876th amiralitaheri 846 63 10ms 23 Feb 2023 876th RuyiLi 846 63 11ms 1 Apr 2023 876th TaserTheFox 🇺🇸 846 63 11ms 25 May 2023 First Prev 801–880 of 3,628 Next Last