Kata Stats: How many queens? | Codewars
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Rethinking the n queens problem for SQL
This is a version of the classic n queens problem (https://en.wikipedia.org/wiki/Eight_queens_puzzle) but reimagined for SQL!
Imagine an NxN chessboard. You also have N queens. How many possible ways can you place all of the queens on the chessboard such that none of them are threatening eachother?
For example, with a 4x4 board and 4 queens, we can do the following placements:
- q - -
- - - q
q - - -
- - q -- - q -
q - - -
- - - q
- q - -Any other arrangement will lead to us not being able to place all 4 queens without at least one queen being threatened. Therefore, there are 2 solutions.
You should create a function nqueens(n int) which, given an integer n, returns the number of possible solutions on an n by n board with n queens. For example,
nqueens(4)
should return 2.
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