5. Longest Palindromic Substring，longestpalindromic

5. Longest Palindromic Substring，longestpalindromic

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.

代碼如下：（超時）

 1 public class Solution {
 2     public String longestPalindrome(String s) {
 3         if(s.length()==1||s.length()==0)
 4         return s;
 5        
 6         String t=" ",sub=" ";
 7         int count=0,max=0;
 8             char[] ss=s.toCharArray();
 9             for(int i=0;i<ss.length;i++)
10             {
11                 if(ss.length-i+1<=max)
12                 return t;
13                 for(int j=ss.length-1;j>i;j--)
14                 {
15                 if(ss[i]==ss[j]){
16                     sub=s.substring(i,j+1);
17                     count=j-i+1;
18                     if(isPalindrome(sub)&&count>max)
19                     {
20                         t=sub;
21                         max=count;
22                         break;
23                     }
24                     }
25                 }
26             }
27         return t;
28         
29     }
30     public boolean isPalindrome(String a){
31         char[] aa=a.toCharArray();
32         int i=0,j=aa.length-1;
33         while(i<=j)
34         {
35             if(aa[i]==aa[j])
36             {i++;j--;}
37             else return false;
38         }
39         return true;
40     }
41 }