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?
Forsyth–Edwards Notation 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 641st amazingalek 🇳🇴 503 195 431ms 11 Jan 2026 642nd Yewzir 🇧🇪 501 197 10ms 4 Apr 2024 643rd msbranicky 501 231 1ms 28 Sep 2023 644th Babafaba 500 163 10ms 25 Oct 2025 645th logalex8369 🇺🇸 499 192 13ms 18 Dec 2025 646th adoxography 497 164 10ms 22 May 2023 646th nstearns96 🇬🇧 497 164 10ms 12 Nov 2024 646th snydej 497 164 9ms 21 Nov 2024 646th kitotch 497 164 10ms 6 days ago 650th daniel-cardone 497 193 9ms 8 Sep 2023 651st emgordon154 496 124 35ms 26 Jul 2024 652nd Babafaba 495 153 497ms 25 Oct 2025 653rd MeWhenI 🇻🇦 495 163 2ms 1 May 2023 654th rozium 494 165 11ms 11 Oct 2024 654th madex 🇩🇪 494 165 10ms 20 Jul 2025 656th Solathian 491 122 5ms 33 hours ago 657th msbranicky 491 166 10ms 5 Aug 2023 658th Schmitt-Very-Cool 487 273 523ms 26 Sep 2025 659th KatieLG 🇬🇧 486 163 1,247ms 1 May 2023 660th andre-lameirinhas 🇵🇹 485 168 11ms 5 May 2023 660th croc54 485 168 10ms 2 Dec 2024 660th BREMAUCY 🇫🇷 485 168 10ms 21 Aug 2025 663rd msbranicky 484 202 88ms 18 Aug 2023 664th ehulinsky 🇺🇸 482 169 10ms 16 May 2023 664th briankuder 482 169 9ms 20 Jun 2023 666th xPMo 482 198 3ms 28 Jun 2024 667th adoxography 481 128 34ms 22 May 2023 668th kaptsanovb 479 170 10ms 24 Sep 2023 669th TaserTheFox 🇺🇸 477 171 10ms 1 May 2023 670th janbehrens 🇩🇪 477 200 10ms 1 May 2023 671st MeWhenI 🇻🇦 475 528 12ms 28 Aug 2023 672nd CedricGebistorf 474 172 11ms 3 May 2023 672nd inverseLorentz 🇦🇺 474 172 10ms 8 May 2023 672nd stertooy 🇧🇪 474 172 32ms 20 Jun 2024 675th TheZwierzLF 🇵🇱 471 173 14ms 21 May 2025 676th TheZwierzLF 🇵🇱 470 131 37ms 21 Dec 2025 677th klixel 🇨🇦 470 321 184ms 23 Jul 2025 678th prplz 🇦🇺 467 208 1ms 9 May 2023 679th Matter1024 🇮🇳 466 175 10ms 17 Feb 2026 680th celiendonze 🇨🇭 463 176 10ms 3 May 2023 681st PhysicDev 🇫🇷 460 177 10ms 25 May 2023 682nd yuchuehw 458 178 11ms 3 Jan 2024 683rd msbranicky 456 166 435ms 17 Jan 2024 684th mbittner20 455 179 9ms 27 May 2023 684th Wildst 455 179 10ms 7 Jul 2023 686th msbranicky 455 217 2,856ms 9 Jan 2025 687th TheZwierzLF 🇵🇱 454 167 503ms 22 Nov 2025 688th KatieLG-Transpiler 🇬🇧 453 180 9ms 16 Aug 2024 689th MeWhenI 🇻🇦 453 181 144ms 25 Oct 2024 690th HenryTy83 452 212 10ms 3 May 2023 691st bobbysq 448 182 10ms 25 May 2023 692nd bac0id 447 256 469ms 11 Jan 2025 693rd KatieLG 🇬🇧 443 139 32ms 29 Aug 2024 694th Stockoh 🇫🇷 443 184 10ms 1 May 2024 695th AstroOrbis 436 187 10ms 10 Feb 2026 696th Natanaelel 🇸🇪 434 188 10ms 5 May 2023 696th Kloppermand 🇩🇰 434 188 10ms 26 May 2023 696th mdnestor 434 188 10ms 27 May 2024 699th JOrE20 434 375 59ms 15 Feb 2026 700th msbranicky 432 174 169ms 9 Jan 2025 701st epic-programmer-guy 431 298 132ms 15 Apr 2024 702nd Yewzir 🇧🇪 430 228 427ms 11 Feb 2024 703rd KatieLG 🇬🇧 428 311 450ms 19 Oct 2024 704th Mikey-Beep 🇬🇧 427 191 16ms 28 Aug 2023 705th lelbal 424 192 10ms 17 Oct 2024 705th yjgnaw 424 192 10ms 24 Jul 2025 707th rollershutter 422 193 10ms 3 May 2023 708th madex 🇩🇪 421 146 33ms 20 Jul 2025 709th KatieLG-Transpiler 🇬🇧 421 180 526ms 16 Aug 2024 710th dokutan 421 394 1ms 6 Dec 2024 711th te-chnical 418 195 10ms 19 Feb 2026 712th madex 🇩🇪 417 362 252ms 20 Jul 2025 713th adamnielson42 🇺🇸 416 196 9ms 1 May 2023 714th elgan65536 🇺🇸 414 197 9ms 9 Nov 2024 714th Pyroan 414 197 9ms 3 Jan 2026 716th bac0id 413 235 2ms 11 Jan 2025 717th MeWhenI 🇻🇦 413 300 4ms 13 Dec 2023 718th Yewzir 🇧🇪 412 184 555ms 4 Feb 2024 719th Masttest 412 198 9ms 31 Jan 2024 719th yokasuretsu 412 198 10ms 14 Jan 2025 First Prev 641–720 of 853 Next Last