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 641st MeWhenI 🇻🇦 653 204 2ms 11 Sep 2022 642nd jerrandolph 653 280 306ms 19 Dec 2023 643rd Florian-Mt 653 286 300ms 15 Jul 2024 644th WalrusesAreAwesome 652 210 394ms 16 Feb 2026 645th UnderKoen 🇳🇱 652 284 13ms 26 Aug 2025 646th TehFlaminTaco 649 113 33ms 10 Nov 2022 647th thehylian 648 116 16ms 14 Jan 2023 647th zacjl 648 116 17ms 20 Apr 2023 649th Shanethegamer 🇺🇸 648 151 19ms 14 Aug 2024 650th CatsAreFluffy 646 205 142ms 31 Mar 2023 651st CaedenHarper 🇨🇦 646 212 360ms 17 Oct 2025 652nd SirBogman 🇺🇸 646 283 41ms 31 Dec 2023 653rd nwellnhof 🇩🇪 645 62 40ms 4 Jun 2022 653rd KL-Lru 645 62 39ms 29 Dec 2022 653rd KatieLG 🇬🇧 645 62 38ms 2 Oct 2025 656th not-a-pokemon 644 181 1ms 5 Jul 2025 657th brimstonetrader 643 206 148ms 21 Jan 2024 658th DialFrost 🇸🇬 642 99 1,966ms 5 Sep 2025 659th betaveros 642 117 15ms 31 Dec 2022 659th DayDun 🇸🇪 642 117 22ms 22 Jan 2023 659th KasperKivimaeki 🇫🇮 642 117 17ms 1 Jul 2025 659th bzijlema 🇳🇱 642 117 16ms 12 Nov 2025 659th Natanaelel 🇸🇪 642 117 12ms 10 Feb 2026 659th StefanHabel 🇨🇦 642 117 15ms 8 days ago 659th SectorCorruptor 642 117 16ms 34 hours ago 666th ovs-code 🇩🇪 640 105 987ms 27 Oct 2023 667th jupj 🇫🇮 640 182 2ms 16 Sep 2022 667th jared-hughes 640 182 2ms 9 Jan 2023 669th MiffOttah 640 214 427ms 28 Nov 2024 670th Yewzir 🇧🇪 639 211 484ms 9 Feb 2023 671st Florian-Mt 638 115 11ms 27 Oct 2023 672nd NickTheEASDude 🇺🇸 638 154 3ms 18 Sep 2024 673rd bizy-coder 637 118 44ms 6 Aug 2023 673rd Rubiksmath 637 118 40ms 7 Aug 2023 673rd blaztoma 🇱🇹 637 118 42ms 16 Feb 2026 676th DialFrost 🇸🇬 637 287 284ms 29 May 2025 677th edsrzf 🇳🇿 634 175 125ms 10 Jun 2025 678th jared-hughes 634 221 2,874ms 9 Jan 2023 679th Frowny 632 119 118ms 13 Feb 2022 679th prplz 🇦🇺 632 119 15ms 13 Feb 2022 679th bricknellj 632 119 21ms 14 Feb 2023 679th edsrzf 🇳🇿 632 119 21ms 4 Oct 2025 679th ryyyn 🇺🇸 632 119 16ms 8 Feb 2026 684th GolfingSuccess 🇬🇷 631 163 120ms 29 Jul 2025 685th CaedenHarper 🇨🇦 630 101 2,081ms 23 Oct 2025 686th Yewzir 🇧🇪 629 397 2,016ms 15 Nov 2025 687th stefangimmillaro 628 133 5ms 2 Jul 2023 688th dokutan 627 190 201ms 12 Jul 2024 689th TobyBoyne 🇬🇧 626 120 16ms 18 Feb 2022 689th OllieBoyne 🇬🇧 626 120 16ms 18 Feb 2022 689th petroselo 626 120 201ms 12 Apr 2022 689th inventshah 626 120 15ms 15 Nov 2022 689th CaedenHarper 🇨🇦 626 120 16ms 27 Dec 2024 689th Lv0Sys 🇵🇱 626 120 20ms 26 days ago 695th JRaspass 🇬🇧 626 292 324ms 18 May 2022 696th ChiefChippy2 625 64 40ms 12 Feb 2022 696th GrayJoKing 🇦🇺 625 64 38ms 13 Feb 2022 698th SirBogman 🇺🇸 625 92 34ms 23 Apr 2022 699th emgordon154 625 93 136ms 7 Aug 2024 700th MeWhenI 🇻🇦 623 108 360ms 15 Feb 2023 701st targrik 623 134 5ms 14 Aug 2025 702nd elPossenreisser 623 220 400ms 6 May 2022 703rd Beariish 622 158 2ms 27 Mar 2025 704th primo-ppcg 🇹🇭 621 121 22ms 4 Mar 2022 704th EnTerr 621 121 24ms 8 Sep 2024 704th Bulmenisaurus 621 121 12ms 3 Oct 2025 707th madex 🇩🇪 620 188 1ms 10 Apr 2022 708th ovs-code 🇩🇪 619 94 187ms 17 Apr 2025 708th rucin93 🇵🇱 619 94 158ms 13 Jun 2025 710th albanian-laundromat 618 103 2,282ms 25 Oct 2025 711th Shanethegamer 🇺🇸 617 184 42ms 6 Sep 2024 712th annaproxy 617 222 400ms 29 Mar 2022 713th sean-niemann 🇺🇸 616 102 2ms 6 Jun 2023 714th ahmetdemirag 🇨🇾 616 122 15ms 15 Jul 2024 715th emgordon154 616 219 755ms 28 May 2025 716th olivermrose 🇺🇸 615 65 38ms 15 Apr 2022 717th GolfingSuccess 🇬🇷 615 196 128ms 28 Nov 2025 718th janAkali 🇷🇺 615 208 412ms 9 Oct 2024 719th AlephSquirrel 614 108 653ms 21 Jan 2024 720th adlerzei 614 223 408ms 5 May 2022 First Prev 641–720 of 1,185 Next Last