package org.hyz.problem;

import org.apache.commons.lang3.StringUtils;

/**

* 给你一个字符串 s，找到 s 中最长的回文子串。

* 两种情况，一种奇数， 一种偶数

*

* @author huyz

*/

public class Solution_5 {

public static void main(String[] args) {

String s = "abaa";

System.out.println(longestPalindrome(s));

}

public static String longestPalindrome(String s) {

String result = "";

if (StringUtils.isEmpty(s) || s.length() == 1) {

return result;

}

for (int i = 1; i < s.length() - 1; i++) {

String resultTempFirst = mindRise(s, i - 1, i + 1);

String resultTempSecond = mindRise(s, i, i + 1);

boolean resultTempFEmp = StringUtils.isEmpty(resultTempFirst) || resultTempFirst.length() == 1;

boolean resultTempSEmp = StringUtils.isEmpty(resultTempSecond) || resultTempSecond.length() == 1;

if (resultTempFEmp && resultTempSEmp) {

continue;

}

result = result.length() > resultTempFirst.length() ? result : resultTempFirst;

result = result.length() > resultTempSecond.length() ? result : resultTempSecond;

}

return result;

}

public static String mindRise(String s, int lowIndex, int highIndex) {

char[] array = s.toCharArray();

int i = lowIndex;

int j = highIndex;

while (i > 0 && j < s.length() - 1) {

if (array[i] == array[j]) {

i--;

j++;

} else {

break;

}

}

if (array[i] != array[j]) {

i++;

j--;

}

return s.substring(i, j + 1);

}

}