[LeetCode][JavaScript]Longest Palindromic Substring

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, and there exists one unique longest palindromic substring.

https://leetcode.com/problems/longest-palindromic-substring/

每一轮遍历，看看与上个数是否相同，相同就跳过。

找回文的时候，先要向右合并相同的数。

 1 /**
 2  * @param {string} s
 3  * @return {string}
 4  */
 5 var longestPalindrome = function(s) {
 6     var max = -1, res = "", count, i, j;
 7     for(var index = 0; index < s.length; index++){
 8         if(s[index - 1] && s[index] === s[index - 1]){
 9             continue;
10         }
11         count = 1;
12         i = j = index;
13         while(s[j + 1] && s[j + 1] === s[index]){
14             j++, count++;
15         }
16         while(s[i] && s[j] && s[i] === s[j]){
17             count += 2;
18             i--; j++;
19         }
20         if(count > max){
21             max = count;
22             res = s.substring(i + 1, j);
23         }
24     }
25     return res;
26 };