Problem 45239. Checkmate-02

Created by Asif Newaz

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This is an extension of the problem https://www.mathworks.com/matlabcentral/cody/problems/45238-checkmate

If the king is in check, examine the next move of the king. List all those possible moves by which king can avoid the check by the next move.

Otherwise 'checkmate'.

r = king's location
p = position of opponent's pieces

if the king is currently not in check, then he doesn't need to move. so return empty.

for simplicity, assume that the king cannot take out opponent's pieces.

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Last Solution submitted on Apr 19, 2023

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William on 24 Dec 2019

Asif,
I think that several of the problem solutions need review.
1. In problem 2, 'Kf7' should not be in the solution since it is adjacent to 'Ke7'. Isn't the correct result {'Kh7',''Kg7','Kf5'}?
2. In problem 7, the king could take any of the knights. Is the solution listed as pos = [] because there are 3 knights on the board? If so, why is the solution to problem 9 listed as 'checkmate'? If not, a solution to problem 9 would be {'Ka3','Ka2'}. Similar questions apply
to problem 8.
3. Why is 'Kc7' not in the solution of problem 3?
I'm afraid I have a lot to learn about chess!

Asif Newaz on 24 Dec 2019

William,
thanks man. There was a bug in my code regarding the other king. i've corrected it. so
3. solution of 3 -- {Kc7,Kb8}.
1. solution of 2 -- {kg7,kf5} .. but not kh7 -- look out!!! there is a rook in the column-h.
2. In prob-7, the king is not currently in check.so he is not obliged to move. thats why empty.
2. in prob-9, yes the king can take out one of the knights & avoid check. Initially when i wrote this code, i didn't take into account the possibility of the king taking out another piece of the opponent. that would complicate the situation further. I kept it for 'checkmate-03'.

William on 26 Dec 2019

Asif,
Thanks for the clarifications.
In problem 2, I was aware of the rook at h3, but there is also a pawn at h5 that makes Kh7 a legitimate solution I think (one that is harder to detect programmatically). As in problem 9, it complicates the solution a little more than you intended.

Asif Newaz on 26 Dec 2019

william,
yes u're right.
my bad..i didn't see that pawn..there is a lot to look into i guess

Rafael S.T. Vieira on 9 Nov 2022

The problem should state that the king is black since Kd5 is not a valid movement for a white king in the first test. And shouldn't the possible moves for the king follow an order? Or else the function "isequal" will fail if the order of the movements does not match. Test #1 uses CW ordering, and Test#3 uses CCW ordering, for instance. And increasing and decreasing indexes also do not work.

Rafael S.T. Vieira on 9 Nov 2022

Test #10 is wrong. It should return an empty list since the King is not in check (& if he were, Kg5 would also be a valid movement). Tests #8 and #9 are inconsistent because both boards have black kings who are in check and cannot escape, but one returns [] and the other 'checkmate' (assuming the king cannot take other pieces).

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Problem 45239. Checkmate-02

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