题目：
Given a string S, find the longest palindromic substring in S. You may assume that the maximum length of S is 1000, and there exists one unique longest palindromic substring.
思路：
以每个点为基础，寻找回文字符串，两种情况，一种是形如aba，中心店两边是对称的，长度为奇数，另一种是形如aa，长度为偶数。
package string; public class LongestPalindromicSubstring { public String longestPalindrome(String s) { int len = s.length(); String max = ""; for (int i = 0; i < len; ++i) { String res = getStr(s, len, i, i); if (res.length() > max.length()) max = res; if (i + 1 < len && s.charAt(i) == s.charAt(i + 1)) { res = getStr(s, len, i, i + 1); if (res.length() > max.length()) max = res; } } return max; } private String getStr(String s, int len, int left, int right) { while (right < len && left >= 0 && s.charAt(left) == s.charAt(right)) { --left; ++right; } return s.substring(left + 1, right); } public static void main(String[] args) { // TODO Auto-generated method stub LongestPalindromicSubstring l = new LongestPalindromicSubstring(); System.out.println(l.longestPalindrome("aabbcc")); } }
LeetCode - Longest Palindromic Substring
原文：http://www.cnblogs.com/shuaiwhu/p/5032955.html