def solution(dimension, solver=None):
"""Generate binary puzzle solution."""
problem = Problem()
if solver is not None:
problem.setSolver(solver)
else:
problem.setSolver(BacktrackingSolver())
problem.addVariables(range(dimension**2), [0, 1])
for i in range(dimension):
row_positions = range(i * dimension, (i + 1) * dimension)
column_positions = range(i, dimension**2, dimension)
# same number of zeros and ones in each row
problem.addConstraint(ExactSumConstraint(dimension / 2), row_positions)
problem.addConstraint(ExactSumConstraint(dimension / 2),
column_positions)
# maximum two of the same next to each other
for triplet in _nwise(row_positions, 3):
problem.addConstraint(MaxSumConstraint(2), triplet)
problem.addConstraint(MinSumConstraint(1), triplet)
for triplet in _nwise(column_positions, 3):
problem.addConstraint(MaxSumConstraint(2), triplet)
problem.addConstraint(MinSumConstraint(1), triplet)
# unique rows and columns
problem.addConstraint(
FunctionConstraint(partial(_test_uniqueness, dimension=dimension)),
range(dimension**2))
if isinstance(solver, RecursiveBacktrackingSolver):
return problem.getSolutions()
if isinstance(solver, MinConflictsSolver):
return (problem.getSolution(), )
return problem.getSolutionIter()
while end - start < max_time: # The program would wait upto 5 minutes for solving a problem
problem = Problem()
cols = range(N) # Number of Columns
rows = range(N) # Number of Rows
problem.addVariables(cols, rows)
for col1 in cols:
for col2 in cols:
if col1 < col2:
problem.addConstraint(
lambda row1, row2, col1=col1, col2=col2: abs(row1 - row2)
!= abs(col1 - col2) and row1 != row2,
(col1, col2),
)
problem.setSolver(MinConflictsSolver())
start = perf_counter() # Starting Counter
solution = problem.getSolution(
) # Minimum Conflict Solver only returns one solution
end = perf_counter() # Ending Counter
times.append(
(N, end -
start)) # Stores Number of Queens and Time Taken to Solve the Puzzle
N += 1
print('Total Time Taken to Solve The Puzzles using Iterative Approach:')
print('N\t Time')
for time in times:
print(time[0], '\t', str(time[1]) + ' seconds')
