题解 | #最长回文子串#

public class Solution {
    public int getLongestPalindrome(String A, int n) {
        // write code here
        if(A == null){
            return 0;
        }
        if(A.length() <= 1){
            return A.length();
        }
        char[] data = A.toCharArray();
        int right = 0,left = 0;
        boolean[][] dp = new boolean[data.length][data.length];
        //注意遍历不要从 0 到 n-1 ，要从尾到头，需要确保遍历中间的那部分是否有回文都判断过
        for(int i = n-2;i>=0;i--){
            dp[i][i] = true;
            for(int j = i+1;j< data.length;j++){
                //如何才是回文
                if(data[i] == data[j] && ((j - i) < 3  || (i< n && dp[i+1][j-1]))){
                    dp[i][j] = true;
                }
                
                //满足条件
                if(dp[i][j] && (right - left) < (j - i)){
                    left = i;
                    right = j;
                }
            }
        }
        return right - left +1;
    }
}