题解 | #判断回文#

import java.util.*;


public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     * 
     * @param str string字符串 待判断的字符串
     * @return bool布尔型
     */
    public boolean judge (String str) {

        if (str == null || str.length() == 0 || str.length() == 1) {
            return true;
        }

        char[] chars = str.toCharArray();
        int mid = str.length()/2;

        Stack<Character> stack = new Stack<>();

        //abab情况
        if (str.length() % 2 == 0) {

            for (int i = 0; i < chars.length; i++) {
                if (i < mid) {
                    stack.push(chars[i]);
                } else {
                    if (chars[i] != stack.pop()) {
                        return false;
                    }
                }
            }

        } else {//aba情况

            for (int i = 0; i < chars.length; i++) {
                if (i < mid) {
                    stack.push(chars[i]);
                } else if (i >= (mid + 1)) {
                    if (chars[i] != stack.pop()) {
                        return false;
                    }
                }
            }

        }

        return true;
    }
}