[LeetCode] Grind 75 questions (5/75) Valid Palindrome

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class Solution {
    public boolean isPalindrome(String s) {
        s = s.toLowerCase().replaceAll("[^a-z0-9]", "");
        int point = s.length() / 2;

        StringBuffer sb = new StringBuffer(s.substring(s.length() - point));
        return s.substring(0,point).equals(sb.reverse().toString());
    }
}

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class Solution {
    public boolean isPalindrome(String s) {
        s = s.toLowerCase().replaceAll("[^a-z0-9]", "");
        
        int left = 0;
        int right = s.length() - 1;

        while(left < right) {
            if(s.charAt(left++) != s.charAt(right--)) return false;
        }

        return true;
    }
}