[LeetCode]Longest Palindromic Substring最长回文字符串

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.

动态规划 时间：O(n^2)  空间： O（n^2）

public class Solution {
    public String longestPalindrome(String s) {
    	int begin = 0;
    	int maxLength = 1;
    	boolean  table[][] = new boolean [s.length()][s.length()];
    	for(int i = 0;i <s.length();i++){
    			table [i][i] = true;
    	}
    	
    	for(int i = 0;i<s.length()-1;i++){
    		if(s.charAt(i)==s.charAt(i+1)){
    			table[i][i+1] = true;
    			begin = i;
    			maxLength = 2;
    		}
    	}
    	
    	for(int len = 3;len <= s.length();len++){
    		for(int i = 0;i<s.length()-len+1;i++){
    			int j= i+len-1;
    			if(s.charAt(i)==s.charAt(j)&&table[i+1][j-1]){
    				table[i][j] = true;
    				begin = i;
    				maxLength = len;
    			}
    		}
    	}
    	
    	return s.substring(begin, begin+maxLength);        
    }
}