1994-1995 ACM International Collegiate Programming Contest
Rooks Most people participating in the ACM scholastic
programming contest have at some stage been asked: 'Can you give an example of
the type of problems you have to solve there?'. The most common example selected
in response is the 8-queens problem.
Of course, all of you have at one time or the other programmed the 8-queens
problem. So here is a small variation on that theme: determine the number of
ways you can place R rooks on an R × R chess board,
such that no two rooks are on the same file or on the same rank.
Input SpecificationThe first line of input contains an integer
N, specifying the number of test cases. Each of the N test
cases consists of a single positive integer R (1 <= R <=
12) on a line by itself, indicating which R-rooks problem you have to
Output SpecificationFor each test case, output the line '
are S solutions to the R-rooks problem.', where
S is the number of solutions, and R is the size of the
There are 1 solutions to the 1-rooks problem.
There are 2 solutions to the 2-rooks problem.
There are 24 solutions to the 4-rooks problem.