Longest Palindromic Substring

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.

Example:

Input: "babad"

Output: "bab"

Note: "aba" is also a valid answer.

Example:

Input: "cbbd"

Output: "bb"

Code

public String longestPalindrome(String s) {
        /**
         * p[i][j]存储是否为回文串
         */
        boolean p[][] = new boolean[s.length()][s.length()];
        if(s.equals("")||s.length()==1){
            return s;
        }
        int i;
        int j;

        for (i=0;i<s.length();i++){
            for (j=0;j<s.length();j++){
                if(i>=j){//当一个字符的时候为回文串
                    p[i][j] = true;
                }
                else{
                    p[i][j] = false;
                }
            }
        }

        int k; //回文串的长度
        int maxLen=1;
        int m=0;//最长回文串的左下标
        int n=0;//右下标
        for(k=1;k<s.length();k++){
            for (i=0;i+k<s.length();i++){
                j=i+k;
                if(s.charAt(i)==s.charAt(j)){
                    p[i][j]=p[i+1][j-1];
                    if(p[i][j]){
                        maxLen = k+1;
                        m=i;
                        n=j;
                    }
                }
                else{
                    p[i][j]=false;
                }
            }
        }
        return s.substring(m,n+1);
    }