Palindrome detection: Difference between revisions

Palindrome detection (view source)

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Line 303: "Able was I ere I saw Elba!" is inexact "In girum imus nocte, et consumimur igni" is inexact </pre> =={{header\|Action!}}== Line 1,202: palindrome </pre> =={{header\|Bruijn}}== <syntaxhighlight lang="bruijn"> :import std/String . main [<~>0 =? 0] :test (main "tacocat") ([[1]]) :test (main "bruijn") ([[0]]) </syntaxhighlight> =={{header\|Burlesque}}== Line 1,865 ⟶ 1,875: return true }</syntaxhighlight> =={{header\|EasyLang}}== <syntaxhighlight lang="easylang"> func$ reverse s$ . a$[] = strchars s$ for i = 1 to len a$[] div 2 swap a$[i] a$[len a$[] - i + 1] . return strjoin a$[] . func palin s$ . if s$ = reverse s$ return 1 . return 0 . for s$ in [ "rotor" "rosetta" "step on no pets" "été" "🦊😀🦊" ] if palin s$ = 1 print s$ & " is a palindrome" else print s$ & " is not a palindrome" . . </syntaxhighlight> =={{header\|EchoLisp}}== Line 1,984 ⟶ 2,018: <syntaxhighlight lang="lisp">(defun palindrome (s) (string= s (reverse s)))</syntaxhighlight> The version below will work correctly with inexact palindromes, as defined in this exercise: <syntaxhighlight lang="lisp"> (defun test-if-palindrome (text) (setq text (replace-regexp-in-string "[[:space:][:punct:]]" "" text)) ; remove spaces and punctuation, by replacing them with nothing (string-equal-ignore-case text (reverse text))) ; ignore case when looking at reversed text </syntaxhighlight> {{out}} <pre> (test-if-palindrome "A man, a plan, a canal, Panama") t </pre> =={{header\|Erlang}}== Line 2,695 ⟶ 2,743: return true }</syntaxhighlight> =={{header\|GolfScript}}== ===Recursive=== <syntaxhighlight lang="golfscript">{.,1>{(\)@={pal}0if}1if\;}:pal;</syntaxhighlight> Test program: <syntaxhighlight lang="groovy">"ABBA" pal "a" pal "13231+464+989=989+464+13231" pal "123 456 789 897 654 321" pal</syntaxhighlight> {{out}} <pre>1 1 1 0</pre> =={{header\|Groovy}}== Line 3,192 ⟶ 3,259: =={{header\|langur}}== <syntaxhighlight lang="langur">val .ispal = ffn(.s) { len(.s) > 0 and .s == ~~s2s~~reverse .s, ~~len(.s)..1~~} val .tests = h{ "": false, "z": true, Line 5,142 ⟶ 5,209: 'ingirumimusnocteetconsumimurigni palindrome? n:put </syntaxhighlight> =={{header\|Refal}}== <syntaxhighlight lang="refal">$ENTRY Go { = <Test 'rotor'> <Test 'racecar'> <Test 'RACEcar'> <Test 'level'> <Test 'rosetta'> <Test 'A man, a plan, a canal: Panama'> <Test 'Egad, a base tone denotes a bad age'> <Test 'This is not a palindrome'>; }; Test { e.W, <Palindrome e.W> <InexactPalindrome e.W>: { True s.1 = <Prout e.W ': exact palindrome'>; s.1 True = <Prout e.W ': inexact palindrome'>; False False = <Prout e.W ': not a palindrome'>; }; }; InexactPalindrome { e.W = <Palindrome <Filter ('ABCDEFGHIJKLMNOPQRSTUVWXYZ') <Upper e.W>>>; }; Filter { (e.Keep) = ; (e.Keep) s.C e.W, e.Keep: { e.1 s.C e.2 = s.C <Filter (e.Keep) e.W>; e.1 = <Filter (e.Keep) e.W>; }; }; Palindrome { = True; s.C = True; s.C e.W s.C = <Palindrome e.W>; e.X = False; };</syntaxhighlight> {{out}} <pre>rotor: exact palindrome marinus@frankenstein:~/refal$ refc palin && refgo palin Refal-5 Compiler. Version PZ Jan 25 2024 Copyright: Refal Systems Inc. rotor: exact palindrome racecar: exact palindrome RACEcar: inexact palindrome level: exact palindrome rosetta: not a palindrome A man, a plan, a canal: Panama: inexact palindrome Egad, a base tone denotes a bad age: inexact palindrome This is not a palindrome: not a palindrome</pre> =={{header\|REXX}}== Line 5,209 ⟶ 5,328: </syntaxhighlight> =={{header\|RPL}}== ≪ "" OVER SIZE 1 '''FOR''' j OVER j DUP SUB + -1 '''STEP''' == ≫ ‘<span style="color:blue">XPAL?</span>’ STO ====Stretch==== RPL does not support Unicode. To detect inexact palindromes, we just need a clean-up word: ≪ "" 1 3 PICK SIZE '''FOR''' j OVER j DUP SUB '''IF''' DUP "a" ≥ OVER "z" ≤ AND '''THEN''' NUM 32 - CHR '''END''' '''IF''' DUP "A" ≥ OVER "Z" ≤ AND '''THEN''' + '''ELSE''' DROP '''END''' '''NEXT''' SWAP DROP ≫ ‘<span style="color:blue">AZONLY</span>’ STO ≪ <span style="color:blue">AZONLY</span> "" OVER SIZE 1 '''FOR''' j OVER j DUP SUB + -1 '''STEP''' == ≫ ‘<span style="color:blue">IPAL?</span>’ STO "rotor" <span style="color:blue">XPAL?</span> "In girum imus nocte et consumimur igni." <span style="color:blue">IPAL?</span> {{out}} <pre> 2: 1 1: 1 </pre> =={{header\|Ruby}}== Line 5,247 ⟶ 5,395: iterative 0.062000 0.000000 0.062000 ( 0.055000) recursive 16.516000 0.000000 16.516000 ( 16.562000)</pre> =={{header\|Rhovas}}== Simplest solution using <code>String.reverse</code>: <syntaxhighlight lang="scala"> func isPalindromeReverse(string: String): Boolean { return string == string.reverse(); } </syntaxhighlight> Alternate character-based solution using pattern matching. Unlike <code>String.reverse</code>, this has limited unicode support due to surrogates (code points split into multiple characters). <syntaxhighlight lang="scala"> func isPalindromeChars(chars: List<String>): Boolean { match (chars) { []: return true; [elem]: return true; [first, middle*, last]: return first == last && isPalindromeChars(middle); } } </syntaxhighlight> Overall result and test cases: <syntaxhighlight lang="scala"> func isPalindrome(string: String): Boolean { return isPalindromeReverse(string) && isPalindromeChars(string.chars); } assert isPalindrome(""); assert isPalindrome("f"); assert isPalindrome("noon"); assert isPalindrome("kayak"); assert isPalindrome("step on no pets"); assert !isPalindrome("palindrome"); assert !isPalindrome("A man, a plan, a canal - Panama!"); //inexact assert isPalindrome("§★♖★§"); //single utf16 code points assert isPalindromeReverse("🗲"); //string reverse handles surrogates assert !isPalindromeChars("🗲".chars); //.chars splits surrogates into two chars </syntaxhighlight> =={{header\|Run BASIC}}== <syntaxhighlight lang="runbasic">data "My dog has fleas", "Madam, I'm Adam.", "1 on 1", "In girum imus nocte et consumimur igni" for i = 1 to 4 read w$ print w$;" is ";isPalindrome$(w$);" Palindrome" next ~~FUNCTION~~function isPalindrome$(str$) for i = 1 to len(str$) a$ = upper$(mid$(str$,i,1)) if (a$ >= "A" and a$ <= "Z") or (a$ >= "0" and a$ <= "9") then b$ = b$ + a$: c$ = a$ + c$ next i if b$ <> c$ then isPalindrome$ = "not"~~</syntaxhighlight>~~ end function</syntaxhighlight> {{out}} <pre>My dog has fleas is not Palindrome Line 5,801 ⟶ 5,992: console.log(isPalindrome('Я иду с мечем судия')) </syntaxhighlight> =={{header\|Uiua}}== Does not ignore spaces. <syntaxhighlight lang="uiua">≍⇌."tacocat"</syntaxhighlight> =={{header\|UNIX Shell}}== Line 5,987 ⟶ 6,182: =={{header\|Wren}}== <syntaxhighlight lang="~~javascript~~wren">var isPal = Fn.new { \|word\| word == ((word.count > 0) ? word[-1..0] : "") } System.print("Are the following palindromes?")