CSE505/Assignment1/A/queens.P

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2024-02-22 01:07:29 -05:00
between(I, J, K) :-
I =< J,
( I = K
; I1 is I+1,
between(I1, J, K)
).
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legal_queens(N, Row, []) :- N =:= Row - 1.
legal_queens(N, Row1, [(Row1, Col1)|Queens]) :-
Row1 < N + 1,
Row2 is Row1 + 1,
legal_queens(N, Row2, Queens),
between(1,N,Col1),
no_attacks((Row1, Col1), Queens).
no_attacks(_, []).
no_attacks((Row1, Col1), [(Row2, Col2)|OtherQueens]) :-
Row1 \= Row2,
Col1 \= Col2,
abs(Row1 - Row2) =\= abs(Col1 - Col2),
no_attacks((Row1, Col1), OtherQueens).
n_queens(N, Solution) :-
legal_queens(N, 1, Solution).
one_queens(N, Solution) :-
legal_queens(N, 1, Solution), !.
printNQueen(N) :- n_queens(N, Solution), write(Solution), write('\n'), fail.
printNQueen(_).
printOneQueen(N) :- one_queens(N, Solution), write(Solution), write('\n'), fail.
printOneQueen(_).
timeNQueen(N) :- cputime(X), printNQueen(N), cputime(Y), T is Y-X, write(T).
timeOneQueen(N) :- cputime(X), printOneQueen(N), cputime(Y), T is Y-X, write(T).