5. Longest Palindromic Substring

5. 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.

Example:

Input: "babad"

Output: "bab"

Note: "aba" is also a valid answer.

 

Example:

Input: "cbbd"

Output: "bb"

/**
 * @param {string} s
 * @return {string}
 */
var longestPalindrome = function(s) {
    var start = 0;
    var max_len = 0;
    var len = s.length;
    if(len < 2){
        return s;
    }
    
  

    for(var i =0;i< len - 1;i++){
        
          check(i,i);
          check(i,i+1);
    }
    
    return s.substring(start,start+max_len);
    
    function check(left,right){
        
       while(left>=0 && right < len && s.charAt(left) == s.charAt(right)){
            left--;
            right++;
        }
        
        if(right-left-1 > max_len){
            
            max_len = right-left-1;
            start = left+1;
           
        }
        
    }
    
};