LeetCode5:Longest Palindromic Substring

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.

一、题目描述

求最长回文子字符串，意思是从给定字符串中找出最长的回文子串，例如，字符串”abcdcbef“，它的最长回文子串就是"bcdcb"

二、解题思路

动态规划的经典例子

class Solution {public:string longestPalindrome(string s) {const int n = s.size();bool f[n][n];fill_n(&f[0][0], n*n, false);size_t max_len = 1, start = 0;for (size_t i = 0; i < s.size(); i++){f[i][i] = true;for (size_t j = 0; j < i; j++){f[j][i] = (s[j] == s[i] && (i - j < 2 || f[j + 1][i - 1]));if (f[j][i] && max_len < (i - j + 1)){max_len = i - j + 1;start = j;}}}return s.substr(start, max_len);}};