647. Palindromic Substrings(#1 ).java

class Solution {
    public int countSubstrings(String s) {
        if (s == null || s.length() < 0) return 0;
        int count = 0, len = s.length();
        boolean[][] isPalindrome = new boolean[len][len];
        for (int i = len - 1; i >= 0; i--) {
            for (int j = i; j < len; j++) {
                if (s.charAt(i) == s.charAt(j) && (j - i < 2 || isPalindrome[i + 1][j - 1])) {
                    isPalindrome[i][j] = true;
                    count++;
                }
            }
        }
        return count;
    }
}