【DP&字符串】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.

用DP，d[i][j]表示字符串i到j是否为回文

public class Solution {
    public String longestPalindrome(String s) {
        int max = 0;
        int len = s.length();
        int maxL = 0;
        int maxR = 0;
        for(int i=0; i<len; i++){
            int l=i;
            int r=i+1;
            while(l>=0 && r<len && s.charAt(l)==s.charAt(r)){
                if(max < r-l+1){
                    max = r-l+1;
                    maxL = l;
                    maxR = r;
                }
                l--;
                r++;
            }
            
            l = i;
            r = i;
            while(l>=0 && r<len && s.charAt(l)==s.charAt(r)){
                if(max < r-l+1){
                    max = r-l+1;
                    maxL = l;
                    maxR = r;
                }
                l--;
                r++;
            }
        }
        return s.substring(maxL, maxR+1);
    }
}