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Problem

Valid Palindrome

LeetCode #125Easy
Converging pointers · skip non-alphanumerics

Given a string, return true if it is a palindrome considering only alphanumeric characters and ignoring case.

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Brute · clean + reverse
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1clean ← lowercased alphanumerics of s
2return clean == reverse(clean)
state
  • cleaned"racecar"

line 1A string is a palindrome if it reads the same forwards and backwards, ignoring case and non-alphanumeric characters. Easiest idea: strip those out, lowercase, and compare to the reverse.