[刷题]Longest Common Substring

[LintCode]Longest Common Substring

不是标准的dp

public class Solution {
    /**
     * @param A, B: Two string.
     * @return: the length of the longest common substring.
     */
    public int longestCommonSubstring(String A, String B) {
        // 2015-05-19 O(n^2)
        if (A == null || B == null || A.length() == 0 || B.length() == 0) {
            return 0;
        }
        int m = A.length();
        int n = B.length();
        int[][] lcs = new int[m + 1][n + 1];
        for (int i = 0; i <= m; i++) {
            lcs[i][0] = 0;
        }
        for (int j = 1; j <= n; j++) {
            lcs[0][j] = 0;
        }
        
        int max = 0;
        for (int i = 1; i <= m; i++) {
            for (int j = 1; j <= n; j++) {
                if (A.charAt(i - 1) == B.charAt(j - 1)) {
                    lcs[i][j] = lcs[i - 1][j - 1] + 1;
                    max = Math.max(max, lcs[i][j]);
                } else {
                    lcs[i][j] = 0;
                }
            }
        }
        return max;
    }
}