This question is part of NeetCode150 series.
Problem Description
A phrase is a palindrome if, after converting all uppercase letters into lowercase letters and removing all non-alphanumeric characters, it reads the same forward and backward. Alphanumeric characters include letters and numbers.
Given a string s, return true if it is a palindrome, or false otherwise.
Solution
Two Pointer Approach
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class Solution {
public boolean isPalindrome(String s) {
s = s.toLowerCase();
int i=0;
int j=s.length()-1;
while(i<j){
if(!Character.isLetterOrDigit(s.charAt(i))){ i++; continue;}
if(!Character.isLetterOrDigit(s.charAt(j))){ j--; continue;}
if(s.charAt(i) != s.charAt(j)) return false;
i++; j--;
}
return true;
}
}