算法题之UVA 11081 Strings（dp）

算法题之UVA 11081 Strings（dp）2014-04-10string by combining two subsequences from the first two strings.

After deleting 0 or more characters from a string we can get its subsequence. For example “a”, “b”, “c”, “ab”, “ac”, “bc” and “abc” all the strings are the subsequences of “abc”. A subsequence may also be empty.

Now suppose there are two subsequences “abc” and “de”. By combining them you can get the followingstrings “abcde”, “abdce”, “abdec”, “adbce”, “adbec”, “adebc”, “dabce”, “dabec”, “daebc” and “deabc”.

Input

The first line of the input contains a single integer T （0<T<271） indicating the number of test cases. Each test case contains 3 strings containing only lowercase characters. The lengths of the strings are between 1 and 60.

Output

For each test case output a single integer denoting the number of ways you can construct the third string from the first two string by the above way. The result may be very large. You should output the result%10007.

Sample Input Output for Sample Input

Problemsetter: Abdullah-al-Mahmud

Special Thanks: Md. Kamruzzaman

题意：给定3个字符串，要求出能用a和b子串（包括空串）组合成c串的总数。

思路： dp。。没思路。看题解。。大概看懂了。f[i][j][k]，i，j，k分别表示三个字符串当前的位置。要开两个数组来表示，否则无法表示出空串情况。有点累死LCS问题。。但是这个确实不好想