leetcode

利用动态规划

参考  http://www.cnblogs.com/tenosdoit/p/3675788.html

代码

class Solution {
public:
    string longestPalindrome(string s) {
        
        int length = s.length();
        if(length<=1)
            return s;
        bool flag[length][length];
        memset(flag, 0, sizeof(flag));
        
        int left = 0;
        int right = 0;
        
        flag[0][0] = true;
        for(int i = 1; i < length; ++i)
        {
            flag[i][i] = true;
            flag[i][i-1] = true;
            
        }
        
        for(int k = 2; k <= length; ++k)
            for(int i = 0; i <= length-k; ++i)
            {
                if(s[i]==s[i+k-1]&&flag[i+1][i+k-2])
                {
                    flag[i][i+k-1] = true;
                    if(right-left+1 < k)
                    {
                        left = i;
                        right = i+k-1;
                    }
                    
                }
                
            }
            
        return s.substr(left, right-left+1);
        
        
    }
};