Learn two easy ways to test a Palindrome String: a clean recursive method and a space saving two-pointer loop. Includes code with comments, step-by-step explanation, dry run, and Big-O analysis.<\/p>\n\n\n\n
The [Problem Link<\/span><\/mark><\/a>]<\/strong> is given here for your quick reference.<\/p>\n\n\n Given a string Compare matching characters from the left and right ends and move inwards:<\/p>\n\n\n\n We show two ways to do this:<\/p>\n\n\n\nWhat does the problem ask?<\/h2>\n\n\n\n
s<\/code>, tell whether it reads the same forwards and backwards.
Return True<\/code><\/strong> if it is a palindrome, or False<\/code><\/strong> otherwise.<\/p>\n\n\n\n
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Input<\/th> Output<\/th> Reason<\/th><\/tr><\/thead> \"abba\"<\/code><\/td>True<\/code><\/td>Same letters from both ends.<\/td><\/tr> \"racecar\"<\/code><\/td>True<\/code><\/td>Reads the same both ways.<\/td><\/tr> \"abc\"<\/code><\/td>False<\/code><\/td>a<\/code> \u2260 c<\/code>.<\/td><\/tr>\"a\"<\/code><\/td>True<\/code><\/td>One letter is always a palindrome.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
\n\n\n\nIntuition & Approach<\/h2>\n\n\n\n
Key idea for both methods<\/h3>\n\n\n\n
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while<\/code> loop.<\/li>\n<\/ol>\n\n\n\n
\n\n\n\nCode 1 \u2013 Recursive<\/h2>\n\n\n\n