标签：
题目链接：https://leetcode.com/problems/longest-palindromic-substring/
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.
解题思路：palindromic-substring是指回文串，例如abba、abcba，它有一个特点就是从字符串的中间开始往两边的字符都是一样的。我们可以从字符串的第二个字符开始向左边和右边同时扫描，找到字符长度最长的回文串。示例代码如下：
public class Solution { public String longestPalindrome(String s) { int n = s.length(); if (n <= 1) return s; int maxlen = 1, k, j, a = 0; int l; for (int i = 1; i < n;) { k = i - 1; j = i + 1; //扫描左边与s[i]相同的字符 while (k >= 0 && s.charAt(k) == s.charAt(i)) k--; //扫描右边与是s[i]相同的字符 while (j < n && s.charAt(j) == s.charAt(i)) j++; while (k >= 0 && j < n && s.charAt(k) == s.charAt(j)) { k--; j++; } l = j - k - 1; if (maxlen < l) { a = k + 1; maxlen = l; } i++; } return s.substring(a, a+maxlen); }
【LeetCode OJ】Longest Palindromic Substring
标签：
原文地址：http://www.cnblogs.com/xujian2014/p/4940673.html
