LeetCode-5_Longest Palindrome Substring

/* * main.cpp * *  Created on: 2017年10月16日 *      Author: zhy * *      Given a string s, find the longest palindromic substring in s. You may assume that the maximum length of s is 1000. *      Example: *      Input: "babad" *      Output: "bab" *      Note: "aba" is also a valid answer. *      Example: *      Input: "cbbd" *      Output: "bb" */#include <iostream>#include <hash_map>using namespace std;using namespace __gnu_cxx;class Solution {public:    static const string longestPalindrome(const string& s)    {        //Brute Force暴力穷举法        std::size_t length = s.size();        int longestPalindromeLength = 0;        string ret("");        for(int i = 0;i < length;++i){            for(int j = i+1;j <= length;++j){       //下面使用迭代器来构造string,由于这种构造方法中的迭代器区间是左闭右开的，因此for()条件带上等号                string tmpStr(s.begin()+i,s.begin()+j);                if(true == Solution::isPalindrome(tmpStr)){                    if(tmpStr.size() > longestPalindromeLength){                        ret = tmpStr;                        longestPalindromeLength = tmpStr.size();                    }                }            }        }        return ret;    }    /*判断参数string是否为回文        可以用于得到一个string内的substring组成的所有回文*/    static bool isPalindrome(const string& s)    {        std::size_t length = s.size();        if(length == 0)            return false;        int left = 0;        int right = length-1;        for(;left <= right;left++,right--){            if(s[left] != s[right]){                return false;            }        }        return true;    }};int main(int argc,char *argv[]){    string s("babad");    auto ret = Solution::longestPalindrome(s);    cout << "The longest: " << ret << "\nLength: " << ret.size() << endl;    return 0;}