*Longest Common Substring

Given two strings, find the longest common substring.

Return the length of it.

Example

Given A = "ABCD", B = "CBCE", return 2.

Note

The characters in substring should occur continuously in original string. This is different with subsequence.

Challenge

O(n x m) time and memory.

分析：

九章算法模板：

/**
 * 本代码由九章算法编辑提供。没有版权欢迎转发。
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 */

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 maxlen = 0;
        int xlen = A.length();
        int ylen = B.length();
        for(int i = 0; i < xlen; ++i)
        {
            for(int j = 0; j < ylen; ++j)
            {
                int len = 0;
                while (i + len < xlen && j + len < ylen && 
                    A.charAt(i + len) == B.charAt(j + len))
                        len ++;
                if(len > maxlen)
                    maxlen = len;
            }
        }
        return maxlen;
    }
}