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# copyright 2002-2021 LOGILAB S.A. (Paris, FRANCE), all rights reserved.
# contact http://www.logilab.fr/ -- mailto:contact@logilab.fr
#
# This file is part of logilab-constraint.
#
# logilab-constraint is free software: you can redistribute it and/or modify it
# under the terms of the GNU Lesser General Public License as published by the
# Free Software Foundation, either version 2.1 of the License, or (at your
# option) any later version.
#
# logilab-constraint is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
# for more details.
#
# You should have received a copy of the GNU Lesser General Public License along
# with logilab-constraint. If not, see <http://www.gnu.org/licenses/>.
from logilab.constraint.propagation import Repository, Solver
from logilab.constraint import fd
def queens(size=8, verbose=0):
possible_positions = [(i, j) for i in range(size) for j in range(size)]
variables = []
domains = {}
constraints = []
for i in range(size):
name = "Q%d" % i
variables.append(name)
domains[name] = fd.FiniteDomain(possible_positions)
for q1 in variables:
for q2 in variables:
if q1 < q2:
constraints.append(
fd.make_expression(
(q1, q2),
"%(q1)s[0] < %(q2)s[0] and "
"%(q1)s[1] != %(q2)s[1] and "
"abs(%(q1)s[0]-%(q2)s[0]) != "
"abs(%(q1)s[1]-%(q2)s[1])" % {"q1": q1, "q2": q2},
)
)
r = Repository(variables, domains, constraints)
s = Solver().solve(r, verbose)
print("Number of solutions:", len(s))
if __name__ == "__main__":
import profile
profile.run("queens()", "csp.prof")
import pstats
p = pstats.Stats("csp.prof")
p.sort_stats("time", "calls").print_stats(0.25)
p.sort_stats("cum", "calls").print_stats(0.25)
p.strip_dirs().sort_stats("cum", "calls").print_callers(0.25)
p.strip_dirs().sort_stats("cum", "calls").print_callees()
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