ortools-clone/examples/python/word_square.py

# -*- coding: latin-1 -*-
# Copyright 2010 Hakan Kjellerstrand hakank@bonetmail.com
#
# 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.

"""

  Word square in Google CP Solver.

  From http://en.wikipedia.org/wiki/Word_square
  '''
  A word square is a special case of acrostic. It consists of a set of words,
  all having the same number of letters as the total number of words (the
  'order' of the square); when the words are written out in a square grid
  horizontally, the same set of words can be read vertically.
  '''

  Compare with the following models:
  * MiniZinc: http://www.hakank.org/minizinc/word_square.mzn
  * Comet   : http://www.hakank.org/comet/word_square.co
  * Choco   : http://www.hakank.org/choco/WordSquare.java
  * Gecode  : http://www.hakank.org/gecode/word_square.cpp
  * Gecode  : http://www.hakank.org/gecode/word_square2.cpp
  * JaCoP   : http://www.hakank.org/JaCoP/WordSquare.java
  * Zinc: http://hakank.org/minizinc/word_square.zinc

  This model was created by Hakan Kjellerstrand (hakank@bonetmail.com)
  Also see my other Google CP Solver models:
  http://www.hakank.org/google_or_tools/
"""
import sys
import string
import re
from ortools.constraint_solver import pywrapcp


def main(words, word_len, num_answers=20):

  # Create the solver.
  solver = pywrapcp.Solver("Problem")

  #
  # data
  #
  num_words = len(words)
  n = word_len
  d, rev = get_dict()

  #
  # declare variables
  #
  A = {}
  for i in range(num_words):
    for j in range(word_len):
      A[(i, j)] = solver.IntVar(0, 29, "A(%i,%i)" % (i, j))

  A_flat = [A[(i, j)] for i in range(num_words) for j in range(word_len)]

  E = [solver.IntVar(0, num_words, "E%i" % i) for i in range(n)]

  #
  # constraints
  #
  solver.Add(solver.AllDifferent(E))

  # copy the words to a Matrix
  for I in range(num_words):
    for J in range(word_len):
      solver.Add(A[(I, J)] == d[words[I][J]])

  for i in range(word_len):
    for j in range(word_len):
      # This is what I would like to do:
      # solver.Add(A[(E[i],j)] == A[(E[j],i)])

      # We must use Element explicitly
      solver.Add(solver.Element(A_flat, E[i] * word_len + j) ==
                 solver.Element(A_flat, E[j] * word_len + i))

  #
  # solution and search
  #
  solution = solver.Assignment()
  solution.Add(E)

  # db: DecisionBuilder
  db = solver.Phase(E + A_flat,
                    solver.CHOOSE_FIRST_UNBOUND,
                    solver.ASSIGN_MIN_VALUE)

  solver.NewSearch(db)
  num_solutions = 0
  while solver.NextSolution():
    # print E
    print_solution(E, words)
    num_solutions += 1

  solver.EndSearch()

  print
  print "num_solutions:", num_solutions
  print "failures:", solver.Failures()
  print "branches:", solver.Branches()
  print "WallTime:", solver.WallTime()


#
# convert a character to integer
#
def get_dict():
  alpha = "abcdefghijklmnopqrstuvwxyz<EFBFBD><EFBFBD><EFBFBD>"
  d = {}
  rev = {}
  count = 1
  for a in alpha:
    d[a] = count
    rev[count] = a
    count += 1
  return d, rev


def print_solution(E, words):
  # print E
  for e in E:
    print words[e.Value()]
  print


def read_words(word_list, word_len, limit):
  dict = {}
  all_words = []
  count = 0
  words = open(word_list).readlines()
  for w in words:
    w = string.strip(w).lower()
    # if len(w) == word_len and not dict.has_key(w) and not re.search("[^a-z<><7A><EFBFBD>]",w) and count < limit:
    # Later note: The limit is not needed anymore with Mistral
    if len(w) == word_len and not dict.has_key(w) and not re.search(
        "[^a-z<><7A><EFBFBD>]", w):
      dict[w] = 1
      all_words.append(w)
      count += 1
  return all_words


word_dict = "/usr/share/dict/words"
word_len = 2
limit = 1000000
num_answers = 20

if __name__ == "__main__":

  if len(sys.argv) > 1:
    word_dict = sys.argv[1]
  if len(sys.argv) > 2:
    word_len = int(sys.argv[2])
  if len(sys.argv) > 3:
    limit = int(sys.argv[3])
  if len(sys.argv) > 4:
    num_answers = int(sys.argv[4])

  # Note: I have to use a limit, otherwise it seg faults
  words = read_words(word_dict, word_len, limit)
  print "It was", len(words), "words"
  main(words, word_len, num_answers)