LeetCode 5. Longest Palindromic Substring

Give you a string s, find s The longest palindrome substring in .

Example 1：

Input ：s = “babad”
Output ：“bab”
explain ：“aba” It's the same answer .
Example 2：

Input ：s = “cbbd”
Output ：“bb”

Tips ：

1 <= s.length <= 1000
s It consists only of numbers and English letters

class Solution {
    
public:
    string longestPalindrome(string s) {
    
        ///  There is a horse drawn cart algorithm ,  We can only do this palindrome substring problem , More biased 

        //  Two points  + hash  Difficulty upgrade , It can handle millions of levels 

        //  Violence 
        //  Palindrome string   It can be divided into odd and even numbers  
        string re ;
        for(int i = 0; i < s.size(); i++)
        {
    
            int l = i - 1, r = i + 1;
            while(l >= 0 && r < s.size() && s[l] == s[r] )  l --, r ++;
            if(re.size() < r - l - 1) re = s.substr(l + 1, r - l - 1);  /// l + 1, r - 1

            l = i, r= i + 1;
            while(l >= 0 && r < s.size() && s[l] == s[r] )  l --, r ++;
            if(re.size() < r - l - 1) re = s.substr(l + 1, r - l - 1);
        }
        return re;
    }
};