The Gray Code Decoder and Gray Code Encoder holes will go live in approximately 33 hours. Why not try and solve them ahead of time?
PalindromemordnilaP 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 481st HumanoidCPU 705 90 452ms 2 Sep 2024 482nd error256 705 97 15ms 14 Jan 2026 483rd adriweb 🇫🇷 704 98 2ms 4 Sep 2024 483rd sean-niemann 🇺🇸 704 98 2ms 5 Sep 2024 483rd dokutan 704 98 2ms 14 Sep 2024 486th MeWhenI 🇻🇦 703 88 150ms 1 Sep 2024 486th error256 703 88 154ms 10 Sep 2024 488th Mabeloid 🇳🇴 703 109 10ms 1 Sep 2024 488th MassimoParisi 703 109 10ms 18 Sep 2024 488th klixel 🇨🇦 703 109 9ms 21 Sep 2024 488th NotNoper 703 109 10ms 29 Oct 2024 488th za3k 703 109 10ms 15 Jul 2025 488th RaBa21 🇭🇺 703 109 9ms 18 Jul 2025 488th zgialor-lab 703 109 10ms 17 Dec 2025 495th MostParsingVex 703 152 1,832ms 11 days ago 496th CaedenHarper 🇨🇦 703 187 279ms 8 Nov 2025 497th DialFrost 🇸🇬 702 61 973ms 31 Aug 2025 497th Steffan153 🇫🇮 702 61 712ms 17 Feb 2026 499th ovs-code 🇩🇪 702 128 2ms 1 Sep 2024 500th emgordon154 701 101 9ms 1 Sep 2024 501st snoozingnewt 🇨🇦 699 91 98ms 19 days ago 502nd KatieLG 🇬🇧 697 91 464ms 1 Sep 2024 503rd frosster 🇨🇦 697 99 2ms 21 Mar 2025 504th sean-niemann 🇺🇸 697 114 170ms 7 Sep 2024 505th elgan65536 🇺🇸 697 172 209ms 23 Sep 2024 506th Andrey2001 696 110 10ms 31 Jan 2026 507th MeWhenI 🇻🇦 694 59 1,026ms 13 Jun 2025 508th stefangimmillaro 693 90 2,686ms 14 Nov 2024 509th sean-niemann 🇺🇸 692 107 2ms 23 Aug 2025 510th JunkIce 690 92 490ms 3 Dec 2024 511th aksyristos 690 111 10ms 1 Sep 2024 511th wh3n3v3r 🇨🇿 690 111 9ms 11 Nov 2024 511th AstroOrbis 690 111 10ms 30 Jun 2025 514th emgordon154 690 288 1,906ms 2 Oct 2024 515th JDiLenarda 🇫🇷 687 170 1,331ms 3 Sep 2024 516th GolfingSuccess 🇬🇷 686 131 2ms 1 Sep 2024 517th kaascevich 685 116 2,277ms 15 Sep 2025 518th DialFrost 🇸🇬 682 62 36ms 30 Jan 2025 519th olleicua 🇺🇸 681 104 11ms 11 Sep 2024 519th charliegaming 681 104 9ms 28 Nov 2024 521st DialFrost 🇸🇬 681 118 81ms 22 Jun 2025 522nd error256 680 63 930ms 20 Dec 2025 523rd MeWhenI 🇻🇦 679 117 126ms 2 Sep 2024 523rd stefangimmillaro 679 117 141ms 2 Sep 2024 525th madex 🇩🇪 678 177 230ms 17 Sep 2024 526th BlankSpruce 676 158 66ms 1 Sep 2024 527th dcgjb 674 69 365ms 11 Sep 2024 528th alicethecatwhisperermeow 672 132 421ms 14 Sep 2024 529th stefangimmillaro 671 63 35ms 2 Sep 2024 529th SirBogman 🇺🇸 671 63 36ms 5 Sep 2024 531st madeforlosers 668 106 16ms 23 Oct 2024 532nd chunes3 🇺🇸 668 112 64ms 1 Sep 2024 533rd prestosilver 🇺🇸 668 121 479ms 4 Feb 2026 534th voytxt 🇨🇿 665 93 161ms 17 Apr 2025 535th DialFrost 🇸🇬 663 96 105ms 28 Nov 2025 536th DialFrost 🇸🇬 663 181 227ms 12 Apr 2025 537th dokutan 662 79 182ms 3 Sep 2024 538th dokutan 662 107 11ms 5 Jun 2025 539th LeoCh01 660 116 11ms 1 Sep 2024 540th GolfingSuccess 🇬🇷 660 162 441ms 1 Sep 2024 540th ovs-code 🇩🇪 660 162 2,915ms 1 Sep 2024 542nd msbranicky 657 95 2,665ms 8 Jan 2025 543rd NickTheEASDude 🇺🇸 657 105 2ms 7 Oct 2025 544th Shanethegamer 🇺🇸 657 135 407ms 1 Sep 2024 545th lukechampine 657 200 274ms 7 Jun 2025 545th jerrandolph 657 200 296ms 21 Sep 2025 547th msbranicky 656 136 3ms 1 Sep 2024 548th albanian-laundromat 655 189 44ms 14 Sep 2025 549th m-tkach 🇺🇦 653 169 29ms 9 Feb 2026 550th TFeld00 🇩🇰 651 65 34ms 3 Sep 2024 551st Shanethegamer 🇺🇸 651 95 162ms 8 Jan 2025 552nd ShiraJoseph 🇺🇸 650 109 9ms 22 Sep 2024 553rd msbranicky 648 203 285ms 1 Sep 2024 554th AlephSquirrel 647 248 3ms 29 Sep 2024 555th stefangimmillaro 645 71 1,320ms 3 Sep 2024 556th Waffle3z 645 107 2ms 2 Oct 2024 557th stefangimmillaro 645 151 494ms 6 Oct 2025 558th mrxz 🇳🇱 644 110 10ms 22 Sep 2024 558th weliveinhell 🇭🇹 644 110 9ms 28 Sep 2024 560th Zhenyu-Bo 644 119 9ms 1 Aug 2025 First Prev 481–560 of 770 Next Last