5155：Harry And Magic Box

题目描述

One day, Harry got a magical box. The box is made of n*m grids. There are sparking jewel in some grids. But the top and bottom of the box is locked by amazing magic, so Harry can’t see the inside from the top or bottom. However, four sides of the box are transparent, so Harry can see the inside from the four sides. Seeing from the left of the box, Harry finds each row is shining(it means each row has at least one jewel). And seeing from the front of the box, each column is shining(it means each column has at least one jewel). Harry wants to know how many kinds of jewel’s distribution are there in the box.And the answer may be too large, you should output the answer mod 1000000007.

输入解释

There are several test cases.
For each test case,there are two integers n and m indicating the size of the box. $0 \leq n, m \leq 50$.

输出解释

For each test case, just output one line that contains an integer indicating the answer.

输入样例

1 1
2 2
2 3

输出样例

1
7
25

提示

There are 7 possible arrangements for the second test case.
They are:
11
11

11
10

11
01

10
11

01
11

01
10

10
01

Assume that a grids is '1' when it contains a jewel otherwise not.

来自杭电HDUOJ的附加信息

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heyang

该题目是Virtual Judge题目，来自杭电HDUOJ

题目来源 BestCoder Round #25

源链接： HDU-5155

最后修改于 2020-10-25T23:20:16+00:00 由爬虫自动更新

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通过率 --%

时间上限	内存上限
2000/1000MS(Java/Others)	32768/32768K(Java/Others)