ortools-clone/python/magic_sequence_distribute.py

# Copyright 2010-2011 Google
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

"""Magic sequence problem.

This models aims at building a sequence of numbers such that the number of
occurrences of i in this sequence is equal to the value of the ith number.
It uses an aggregated formulation of the count expression called
distribute().
"""



from google.apputils import app
import gflags
from constraint_solver import pywrapcp

FLAGS = gflags.FLAGS


def main(unused_argv):
  # Create the solver.
  solver = pywrapcp.Solver('magic sequence')

  size = 100
  all_values = range(0, size)
  all_vars = [solver.IntVar(0, size, 'vars_%d' % i) for i in all_values]

  solver.Add(solver.Distribute(all_vars, all_values, all_vars))
  solver.Add(solver.Sum(all_vars) == size)

  solver.NewSearch(solver.Phase(all_vars,
                                solver.CHOOSE_FIRST_UNBOUND,
                                solver.ASSIGN_MIN_VALUE))
  solver.NextSolution()
  print all_vars
  solver.EndSearch()


if __name__ == '__main__':
  app.run()