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22 lines
666 B
Python
22 lines
666 B
Python
# example from https://ericpony.github.io/z3py-tutorial/guide-examples.htm
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from z3 import Int, And, Distinct, If, solve, print_matrix
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# We know each queen must be in a different row.
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# So, we represent each queen by a single integer: the column position
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Q = [ Int('Q_%i' % (i + 1)) for i in range(8) ]
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# Each queen is in a column {1, ... 8 }
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val_c = [ And(1 <= Q[i], Q[i] <= 8) for i in range(8) ]
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# At most one queen per column
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col_c = [ Distinct(Q) ]
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# Diagonal constraint
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diag_c = [ If(i == j,
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True,
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And(Q[i] - Q[j] != i - j, Q[i] - Q[j] != j - i))
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for i in range(8) for j in range(i) ]
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solve(val_c + col_c + diag_c)
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