[LintCode] Longest Common Substring

public class Solution {
    /**
     * @param A, B: Two string.
     * @return: the length of the longest common substring.
     */
    public int longestCommonSubstring(String A, String B) {
        int[][] result = new int[A.length() + 1][B.length() + 1];
        if (A == null || B == null){
            return 0;
        }
        int max = 0;
        for (int i = 1; i <= A.length(); i++){
            for (int j = 1; j <= B.length(); j++){
                if (A.charAt(i - 1) == B.charAt(j - 1)){
                    result[i][j] = result[i - 1][j - 1] + 1;
                } else {
                    result[i][j] = 0;
                }
                max = Math.max(max, result[i][j]);
            }
        }
        return max;
    }
}