Problem 45238. Checkmate

Created by Asif Newaz

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The positions of different chess pieces are given in a cell p .
The position of the king is given as x

Determine if the opponent king is in check for individual scenerios.

x='Kg7'
p={'Qe5','Qg5','Qb5','Qa7'}

output= [1,1,0,1]

N.b.any invalid position should produce 0. u may imagine p as the white pieces and x as the black king for clarity.

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Last Solution submitted on Nov 22, 2025

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William on 21 Dec 2019

Asif,
I really like this problem, but I don't understand why 'h6' has 'Kg7' in check in Problem 2, but 'e1' does not have 'Kf2' in check in Problem 6. Aren't these two situations the same?

Asif Newaz on 22 Dec 2019

William,
the opponent's pawn can never be in row-1. they can only move/check forward.

William on 22 Dec 2019

Asif,
Thanks, but my point is that the pawn is in row-1 in *both* cases, so they should both be in check or neither should be in check. Since you described 'x' as being the 'opponent King', I think that both should be in check.

Asif Newaz on 23 Dec 2019

william,
i might not have understood u totally.
what i meant to say is that -- there are some invalid position/moves. for example, the pawn can jump from a2 to a4 but not from a3 to a5-thats an invalid move. similarly a white pawn can never be at the location a1-- their position starts from a2-so placing a pawn in row-1 is an invalid move.
in test-6, the pawn in e1 could check the king - but its own position is invalid.it could not be in that position in the 1st place. thats why 0.
in test-2,3; the pawn is in h6. a pawn can be in the column-h or row-6.so thats a valid position.
https://en.wikipedia.org/wiki/Pawn_(chess)

William on 23 Dec 2019

Asif,
Aha! Tricky, and very clever. Thanks for posting this interesting problem!

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Problem 45238. Checkmate

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