05. 求最长回文子串

 1 class Solution {
 2     public String longestPalindrome(String s) {
 3        char[] ch = s.toCharArray();
 4         if(ch.length==0){
 5             return "";
 6         }
 7         int left = 0;
 8         int right = 0;
 9         int index = 0;
10         int j =0;
11         int k=0;
12         for(int i=1;i<ch.length;i++){
13             while(index<i){
14                 for(j=index,k=0;j<=i-k;j++,k++){
15                     if(ch[j] != ch[i-k]){
16                         break;
17                     }
18                 }
19                 if(j>=i-k){
20                     if(i-index>right-left) {
21                         left = index;
22                         right = i;
23                     }
24                 }
25                 index++;
26             }
27            index = 0;
28         }
29 
30         StringBuffer stringBuffer = new StringBuffer();
31         while(left<=right) {
32             stringBuffer.append(ch[left]);
33             left++;
34         }
35         return stringBuffer.toString();
36     }
37 }