LintCode-最长公共子串

题目描述：

　　给出两个字符串，找到最长公共子串，并返回其长度。

 注意事项

　　子串的字符应该连续的出现在原字符串中，这与子序列有所不同。

样例

　　给出A=“ABCD”，B=“CBCE”，返回 2

public class Solution {
    /**
     * @param A, B: Two string.
     * @return: the length of the longest common substring.
     */
    public int longestCommonSubstring(String A, String B) {
        // write your code here
        int maxLength = 0;
        if(A==null || B==null)
            return 0;
        for (int i = 0; i < A.length(); i++) {
            for (int j = 0; j < B.length(); j++) {
                if (B.charAt(j) == A.charAt(i)) {
                    int k = j + maxLength, l = i + maxLength;
                    if (k >= B.length() || l >= A.length())
                        break;
                    else if(B.substring(j, j + maxLength).equals(A.substring(i, i + maxLength))) {

                        while (B.charAt(k) == A.charAt(l)) {
                            maxLength++;
                            k++;
                            l++;
                            if (k >= B.length() || l >= A.length())
                                break;

                        }
                    }
                }
            }
        }
        return maxLength;
    }
}