125. 验证回文串

/**
 * @Description 回文串验证直接使用对撞指针即可
 * 这道题其实主要是考察对撞指针的应用和String库函数的应用
 * @Date 2022/1/9 6:09 下午
 * @Author wuqichuan@zuoyebang.com
 **/
public class Solution {
    public boolean isPalindrome(String s) {
        //先把只考虑字符，剔除符号
        StringBuffer sgood = new StringBuffer();
        int length = s.length();
        for (int i = 0; i < length; i++) {
            char ch = s.charAt(i);
            if (Character.isLetterOrDigit(ch)) {
                sgood.append(Character.toLowerCase(ch));
            }
        }
        int left = 0;
        int right = sgood.length() - 1;
        while (left < right) {
            if (sgood.charAt(left) != sgood.charAt(right)) {
                return false;
            }
            ++left;
            --right;
        }
        return true;
    }
}