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;
     }
 }