Longest Palindromic Substring

1. Title

Longest Palindromic Substring

2. Http address

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

3. The question

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.

 

4. My code (AC)

 1     // Accepted
 2     public static String longestPalindrome(String s) {
 3          
 4         if ( s == null)
 5             return s;
 6         int len = s.length();
 7         if ( len <= 1)
 8             return s;
 9         boolean isPalindrome[][] = new boolean[len][len];
10         int start = 0;
11         int maxLen = 0;
12         for(int i = 0 ; i < len; i++)
13         {
14             isPalindrome[i][i] = true;
15             start = i;
16             maxLen = 1;
17         }
18         
19         for(int i = 0 ; i < len - 1; i++)
20         {
21             if ( s.charAt(i) == s.charAt(i+1)){
22                 isPalindrome[i][i+1] = true;
23                 start = i;
24                 maxLen = 2;
25             }
26         }
27         
28         for( int i = len - 3; i >=0 ; i--)
29         {
30             for( int j = i + 2; j < len; j++)
31             {
32                 if( s.charAt(i) == s.charAt(j) && isPalindrome[i+1][j-1])
33                 {
34                     isPalindrome[i][j] = true;
35                     if ( maxLen < (j - i + 1))
36                     {
37                         start = i;
38                         maxLen = j - i + 1;
39                     }
40                 }
41             }
42         }
43         for( int i = 0 ; i < len ; i++)
44         {
45             System.out.println();
46             for( int j = 0 ; j < len ; j++)
47             {
48                 System.out.print(" " + isPalindrome[i][j]);
49             }
50             System.out.println();
51         }
52         System.out.println(start);
53         System.out.println(maxLen);
54         return s.substring(start, start + maxLen);
55     }

 

posted @ 2015-11-16 20:55  ordi  阅读(133)  评论(0)  编辑  收藏  举报