Queen Attack

Instructions

Given the position of two queens on a chess board, indicate whether or not they are positioned so that they can attack each other.

In the game of chess, a queen can attack pieces which are on the same row, column, or diagonal.

A chessboard can be represented by an 8 by 8 array.

So if you are told the white queen is at c5 (zero-indexed at column 2, row 3) and the black queen at f2 (zero-indexed at column 5, row 6), then you know that the set-up is like so:

  a b c d e f g h
8 _ _ _ _ _ _ _ _ 8
7 _ _ _ _ _ _ _ _ 7
6 _ _ _ _ _ _ _ _ 6
5 _ _ W _ _ _ _ _ 5
4 _ _ _ _ _ _ _ _ 4
3 _ _ _ _ _ _ _ _ 3
2 _ _ _ _ _ B _ _ 2
1 _ _ _ _ _ _ _ _ 1
  a b c d e f g h

You are also able to answer whether the queens can attack each other. In this case, that answer would be yes, they can, because both pieces share a diagonal.

Track Specific Notes

For this track, each queen's position will be represented as a list containing the row and the column. You should assume all inputs are valid, there's no need to report errors.

Running and testing your solutions

From the command line

Simply type make chez if you're using ChezScheme or make guile if you're using GNU Guile. Sometimes the name for the scheme binary on your system will differ from the defaults. When this is the case, you'll need to tell make by running make chez chez=your-chez-binary or make guile guile=your-guile-binary.

From a REPL

• Enter (load "test.scm") at the repl prompt.
• Develop your solution in queen-attack.scm reloading as you go.
• Run (test) to check your solution.

Failed Test Cases

If some of the test cases fail, you should see the failing input and the expected output. The failing input is presented as a list because the tests call your solution by (apply queen-attack input-list). To learn more about apply see The Scheme Programming Language -- Chapter 5

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Source

J Dalbey's Programming Practice problems