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?
Card Number Validation in all languages in bytes. 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 Bytes Time Submitted 801st luca1339 472 198 425ms 4 Nov 2024 802nd Maximizer02 471 201 12ms 1 Oct 2024 803rd ejini6969 469 102 39ms 14 Jun 2025 804th zyc-2024 🇨🇳 469 170 10ms 5 Oct 2024 805th jbjd 468 151 2ms 4 Feb 2026 806th snoozingnewt 🇨🇦 467 200 230ms 2 Nov 2025 807th ComputerKWasTaken 🇺🇸 466 171 10ms 14 Oct 2024 808th snoozingnewt 🇨🇦 465 121 229ms 27 Nov 2025 809th iczelia 🇩🇪 462 94 2ms 23 Sep 2025 810th Jacob385 462 202 418ms 2 Oct 2024 811th navier-1 461 173 10ms 22 Sep 2025 812th madex 🇩🇪 460 104 37ms 2 Oct 2024 813th TheZwierzLF 🇵🇱 456 105 37ms 8 Jan 2026 814th snoozingnewt 🇨🇦 455 149 5ms 2 Nov 2025 815th IISResetMe 453 103 583ms 27 Nov 2025 816th clayboll99 453 176 10ms 10 Jul 2025 817th snoozingnewt 🇨🇦 452 96 2ms 2 Nov 2025 818th dokutan 451 63 3ms 26 Nov 2024 819th snoozingnewt 🇨🇦 451 176 2ms 2 Nov 2025 820th muser-logiccpu 🇺🇦 451 177 18ms 9 Aug 2025 821st OSYCh314 🇦🇺 448 178 10ms 2 Nov 2024 822nd dokutan 445 109 10ms 19 Oct 2024 823rd grey0ut 444 105 435ms 11 Jan 2025 824th calum12345 443 180 10ms 26 Mar 2025 825th Yewzir 🇧🇪 442 171 12ms 26 Dec 2024 826th MyXoToD 🇩🇪 441 146 10ms 26 May 2025 827th CheeseCake628 🇳🇴 439 151 521ms 18 Oct 2025 828th zt14427 438 182 11ms 27 Dec 2024 829th IoLimmer 436 183 10ms 10 Oct 2024 830th KatieLG 🇬🇧 433 183 2ms 2 Oct 2025 831st KatieLG 🇬🇧 431 108 6ms 13 Oct 2024 832nd snoozingnewt 🇨🇦 431 111 34ms 2 Nov 2025 833rd varhammer 431 223 11ms 23 Feb 2025 834th estomagordo 🇳🇱 429 186 10ms 15 Jul 2025 835th dokutan 426 132 301ms 3 Oct 2024 836th JOrE20 424 136 1,020ms 7 Dec 2025 837th MeWhenI 🇻🇦 424 143 6ms 2 Oct 2024 838th Arkadios200 417 196 106ms 21 Oct 2025 839th aksyristos 411 172 2ms 23 Nov 2025 840th snoozingnewt 🇨🇦 411 267 29ms 18 Dec 2025 841st Mabeloid 🇳🇴 405 159 16ms 12 Oct 2024 842nd snoozingnewt 🇨🇦 404 223 96ms 2 Nov 2025 843rd Ralac07 🇦🇺 398 162 11ms 3 Oct 2024 844th snoozingnewt 🇨🇦 392 276 40ms 6 Dec 2025 845th dieggsy 389 247 18ms 10 Oct 2024 846th snoozingnewt 🇨🇦 388 313 40ms 2 Nov 2025 847th fischfood 385 176 5ms 22 Oct 2024 848th JOrE20 385 191 169ms 27 Jan 2026 849th ehulinsky 🇺🇸 384 158 5ms 2 Apr 2025 850th c0d3-4-F00d 🇩🇪 384 184 2ms 9 Jan 2025 851st KatieLG 🇬🇧 375 218 114ms 21 Nov 2025 852nd RobGLambert 375 232 1,388ms 8 Jun 2025 853rd RedzGoose 🇦🇺 371 187 114ms 2 Oct 2024 854th P1nk-P0nk 369 215 3ms 18 Oct 2024 855th gautambp 366 218 11ms 24 Jun 2025 856th snoozingnewt 🇨🇦 360 267 13ms 2 Nov 2025 857th sciencejiho 358 197 2ms 11 Feb 2025 858th The-Wolfson 355 230 110ms 16 Dec 2024 859th Zhenyu-Bo 350 228 11ms 30 Jul 2025 860th EthanJantz 347 230 11ms 5 Sep 2025 861st RobGLambert 342 273 198ms 8 Jun 2025 862nd Ernest1338 340 275 300ms 26 Oct 2024 863rd noahhorlacher 337 191 11ms 7 Dec 2024 864th RobertBurs 336 237 10ms 22 Sep 2025 865th TJK-S 331 241 11ms 25 Oct 2025 865th NoneTheFewer 331 241 11ms 25 Dec 2025 867th JOrE20 314 389 56ms 4 Dec 2025 868th te-chnical 309 258 219ms 4 May 2025 869th snoozingnewt 🇨🇦 303 200 4ms 2 Nov 2025 870th KatieLG 🇬🇧 300 290 2,534ms 1 Oct 2025 871st kasarino 294 240 2ms 8 Feb 2026 872nd KatieLG 🇬🇧 293 241 2ms 1 Oct 2025 873rd fantaize 283 330 201ms 17 days ago 874th ReterikHub 280 310 209ms 17 Jan 2025 875th Mikey-Beep 🇬🇧 273 349 16ms 12 Aug 2025 876th MeWhenI 🇻🇦 272 407 119ms 6 Oct 2024 877th arebbsba 269 296 11ms 9 Jan 2025 878th kasarino 267 299 11ms 8 Feb 2026 879th kasarino 258 373 44ms 8 Feb 2026 880th benanlam 249 320 10ms 21 Dec 2025 First Prev 801–880 of 917 Next Last