The Gray Code Decoder and Gray Code Encoder holes will go live in approximately 6 days. Why not try and solve them ahead of time?
Reverse Polish 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 801st Heathcorp 🇦🇺 561 134 26ms 7 Oct 2022 801st madex 🇩🇪 561 134 23ms 9 Jul 2024 801st LostSyntax21 🇬🇧 561 134 24ms 2 Dec 2024 804th Shanethegamer 🇺🇸 561 184 11ms 4 Oct 2024 805th Shanethegamer 🇺🇸 560 149 5ms 2 Jul 2023 806th targrik 559 327 282ms 3 Jul 2025 807th janbehrens 🇩🇪 557 135 27ms 1 Jul 2022 807th mwja 557 135 16ms 21 Aug 2024 809th FlorianCassayre 🇫🇷 556 132 12ms 18 Sep 2022 810th emgordon154 555 72 37ms 20 Nov 2024 810th Lv0Sys 🇵🇱 555 72 37ms 6 Dec 2025 812th destofr 554 231 383ms 30 Dec 2022 813th martinnorling 🇸🇪 553 136 31ms 15 Feb 2022 813th adoxography 553 136 15ms 20 Mar 2022 813th nullie 553 136 16ms 14 Jun 2022 813th AGoyet 553 136 15ms 17 Jul 2022 813th inverseLorentz 🇦🇺 553 136 22ms 21 Feb 2024 813th HumanoidCPU 553 136 11ms 29 Sep 2024 813th chartung17 553 136 15ms 20 Apr 2025 813th Luke44565 553 136 17ms 10 Aug 2025 813th Bmrl7 553 136 25ms 21 Dec 2025 822nd msbranicky 553 338 260ms 6 Oct 2023 823rd msbranicky 552 244 2,760ms 9 Jan 2025 824th inventshah 551 122 2,463ms 7 Nov 2022 825th iczelia 🇩🇪 550 212 1ms 11 Oct 2025 826th keelimeguy 🇺🇸 550 255 2,844ms 5 Nov 2023 826th yeminghan2021 550 255 64ms 2 Feb 2025 828th KatieLG 🇬🇧 549 74 4ms 19 Mar 2022 829th nstearns96 🇬🇧 549 137 22ms 15 Dec 2022 829th mossprescott 549 137 11ms 19 Jan 2023 829th taesungh 549 137 17ms 15 Oct 2023 829th PyryL 🇫🇮 549 137 21ms 25 Aug 2024 833rd zakariamouhid 548 134 12ms 11 May 2023 834th stellartux 547 123 349ms 24 Dec 2023 835th michelebastione 🇮🇹 545 138 16ms 19 Feb 2022 835th knutae 🇳🇴 545 138 16ms 8 Mar 2022 835th RDShah 545 138 31ms 15 May 2022 835th ImpressedByRocks 545 138 16ms 10 Oct 2024 839th c0d3-4-F00d 🇩🇪 544 214 2ms 24 Feb 2022 840th codewrite 🇬🇧 544 252 393ms 13 May 2025 841st Shanethegamer 🇺🇸 542 116 1ms 5 Nov 2022 841st GolfingSuccess 🇬🇷 542 116 2ms 22 Feb 2026 843rd cefqrn 541 139 16ms 20 Dec 2022 843rd alfonsoalves 541 139 17ms 1 Mar 2024 843rd hiichbindermax 541 139 35ms 19 Sep 2024 843rd jacekwladzinski 541 139 12ms 10 Oct 2025 847th MeWhenI 🇻🇦 540 64 2ms 15 Feb 2022 848th m-tkach 🇺🇦 540 74 51ms 25 Jun 2024 849th hjcafaroUC 539 260 2,890ms 20 Aug 2022 850th bac0id 537 217 1ms 27 Jun 2024 851st MeWhenI 🇻🇦 534 76 6ms 16 Apr 2023 852nd snoozingnewt 🇨🇦 534 253 108ms 8 Oct 2025 853rd SirFireball3521 533 141 38ms 7 Feb 2023 853rd AstroOrbis 533 141 16ms 12 Jul 2025 853rd RaBa21 🇭🇺 533 141 11ms 14 Jul 2025 853rd osNiko 🇧🇷 533 141 17ms 30 Dec 2025 857th MeWhenI 🇻🇦 533 208 115ms 16 Oct 2022 858th neel11235813 531 125 450ms 17 Mar 2024 859th IlkkaTakala 531 264 3,011ms 20 Dec 2023 860th KatieLG 🇬🇧 531 470 1,882ms 21 Nov 2025 861st codewrite 🇬🇧 530 345 271ms 16 Jun 2025 862nd MichalMarsalek 🇨🇿 529 142 17ms 14 Feb 2022 862nd marcin7Cd 529 142 15ms 20 Feb 2022 864th JOrE20 529 357 62ms 16 Feb 2026 865th SniperSmiley 🇺🇸 526 143 17ms 8 Jul 2022 865th Europe2048 526 143 23ms 22 Oct 2024 865th moustave 526 143 11ms 7 Apr 2025 868th varhammer 526 196 5ms 13 Dec 2023 869th janbehrens 🇩🇪 525 128 1,626ms 23 Feb 2022 870th randolchance 522 144 17ms 4 Jan 2024 870th roupiq 🇵🇱 522 144 17ms 1 Mar 2024 870th robin-scragg 522 144 16ms 22 Aug 2025 870th Deppyforce 522 144 17ms 9 Nov 2025 874th warmCabin 522 223 2ms 15 Apr 2022 875th postie77 521 263 382ms 19 May 2023 876th Shanethegamer 🇺🇸 520 224 2ms 28 May 2025 877th MeWhenI 🇻🇦 520 246 400ms 27 Jul 2024 878th DialFrost 🇸🇬 519 77 36ms 25 Dec 2024 879th MeWhenI 🇻🇦 519 255 150ms 13 Feb 2022 880th ovs-code 🇩🇪 519 398 8ms 8 Jul 2024 First Prev 801–880 of 1,185 Next Last