leetcode Longest Palindromic Substring

Longest Palindromic Substring

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Total Accepted: 70417 Total Submissions: 338025 Difficulty: Medium

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.

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算法转自http://www.cnblogs.com/caterpillarofharvard/articles/4245626.html，但是由于本人理解力切佳，所以就在纸上画了画。

代码如下：

// test5LongestPalindromicSubstring.cpp : 定义控制台应用程序的入口点。//#include "stdafx.h"#include "string"#include "vector"using std::string;using std::vector;string longPalindrome(string s){if (s.size() < 2)return s;int center=0, right=0;int max = 0;int j = 0;int n = s.size();vector<int> len;int currentlen = 0;len.push_back(1);for (int i = 1; i < n; i++){if (i <= right){j = 2 * center - i;if (len[j] + i < center){currentlen = len[j];len.push_back(currentlen);continue;}}currentlen = 0;int l = i, r = i;while (l >= 0 && r<n && s[l] == s[r])//注意此处，最后一个判定条件必须放到后面的后面，否则将会出错。{currentlen++;r++;l--;}len.push_back(currentlen);if (currentlen > max){center = i;right = center + currentlen - 1;max = currentlen;}}string result = "";int left = center - max + 1;if (left % 2 == 0)left++;while (left<right){result += s[left];left+=2;}return result;}string longestPalindrome(string s){if (s.size() < 2)return s;string temp = "#";for (int i = 0; i < s.size(); i++){temp += s[i];temp += '#';}return longPalindrome(temp);}int _tmain(int argc, _TCHAR* argv[]){string s = longestPalindrome("aaaba");return 0;}