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2431:Counting Problem

题目描述
      Yes. Counting problem comes again.
      Given a chess board of N*N (N<=500), how many ways are there to put N queens on it so that no queen can attack another?
      Luckily this is not the problem you should solve in this contest. Instead, we have a much easier one here.
      Given a chess board of N*N (N<=500), how many ways are there to put 2*N queens on it so that there are exactly two queens in each row and each column?
      To make it even easier, we will consider one way to be the same with another if it can be transformed to the other one by swapping rows and swapping columns.
输入解释
      The first line of the input is an integer T indicating the number of cases.
      Line 2..T+1 will contain an positive integer N (N <=500) each.
输出解释
      T lines containing your counting results respectively.
      For the number may be very large, you just have to output its module by 1000007.
输入样例
3
2
5
4
输出样例
1
2
2
来自杭电HDUOJ的附加信息
Recommend lcy

该题目是Virtual Judge题目,来自 杭电HDUOJ

源链接: HDU-2431

最后修改于 2020-10-25T22:53:22+00:00 由爬虫自动更新

共提交 0

通过率 --%
时间上限 内存上限
5000/1000MS(Java/Others) 32768/32768K(Java/Others)