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# Copyright 2010 Hakan Kjellerstrand hakank@gmail.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.
"""

  Crosswords in Google CP Solver.

  This is a standard example for constraint logic programming. See e.g.

  http://www.cis.temple.edu/~ingargio/cis587/readings/constraints.html
  '''
  We are to complete the puzzle

     1   2   3   4   5
   +---+---+---+---+---+       Given the list of words:
 1 | 1 |   | 2 |   | 3 |             AFT     LASER
   +---+---+---+---+---+             ALE     LEE
 2 | # | # |   | # |   |             EEL     LINE
   +---+---+---+---+---+             HEEL    SAILS
 3 | # | 4 |   | 5 |   |             HIKE    SHEET
   +---+---+---+---+---+             HOSES   STEER
 4 | 6 | # | 7 |   |   |             KEEL    TIE
   +---+---+---+---+---+             KNOT
 5 | 8 |   |   |   |   |
   +---+---+---+---+---+
 6 |   | # | # |   | # |       The numbers 1,2,3,4,5,6,7,8 in the crossword
   +---+---+---+---+---+       puzzle correspond to the words
                               that will start at those locations.
  '''

  The model was inspired by Sebastian Brand's Array Constraint cross word
  example
  http://www.cs.mu.oz.au/~sbrand/project/ac/
  http://www.cs.mu.oz.au/~sbrand/project/ac/examples.pl


  Also, see the following models:
  * MiniZinc: http://www.hakank.org/minizinc/crossword.mzn
  * Comet: http://www.hakank.org/comet/crossword.co
  * ECLiPSe: http://hakank.org/eclipse/crossword2.ecl
  * Gecode: http://hakank.org/gecode/crossword2.cpp
  * SICStus: http://hakank.org/sicstus/crossword2.pl
  * Zinc: http://hakank.org/minizinc/crossword2.zinc

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


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

#
# data
#
alpha = "_abcdefghijklmnopqrstuvwxyz"
a = 1
b = 2
c = 3
d = 4
e = 5
f = 6
g = 7
h = 8
i = 9
j = 10
k = 11
l = 12
m = 13
n = 14
o = 15
p = 16
q = 17
r = 18
s = 19
t = 20
u = 21
v = 22
w = 23
x = 24
y = 25
z = 26

num_words = 15
word_len = 5
AA = [
    [h, o, s, e, s],  # HOSES
    [l, a, s, e, r],  # LASER
    [s, a, i, l, s],  # SAILS
    [s, h, e, e, t],  # SHEET
    [s, t, e, e, r],  # STEER
    [h, e, e, l, 0],  # HEEL
    [h, i, k, e, 0],  # HIKE
    [k, e, e, l, 0],  # KEEL
    [k, n, o, t, 0],  # KNOT
    [l, i, n, e, 0],  # LINE
    [a, f, t, 0, 0],  # AFT
    [a, l, e, 0, 0],  # ALE
    [e, e, l, 0, 0],  # EEL
    [l, e, e, 0, 0],  # LEE
    [t, i, e, 0, 0]  # TIE
]

num_overlapping = 12
overlapping = [
    [0, 2, 1, 0],  # s
    [0, 4, 2, 0],  # s
    [3, 1, 1, 2],  # i
    [3, 2, 4, 0],  # k
    [3, 3, 2, 2],  # e
    [6, 0, 1, 3],  # l
    [6, 1, 4, 1],  # e
    [6, 2, 2, 3],  # e
    [7, 0, 5, 1],  # l
    [7, 2, 1, 4],  # s
    [7, 3, 4, 2],  # e
    [7, 4, 2, 4]  # r
]

n = 8

# declare variables
A = {}
for I in range(num_words):
  for J in range(word_len):
    A[(I, J)] = solver.IntVar(0, 26, "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))

for I in range(num_words):
  for J in range(word_len):
    solver.Add(A[(I, J)] == AA[I][J])

for I in range(num_overlapping):
  # This is what I would do:
  # solver.Add(A[(E[overlapping[I][0]], overlapping[I][1])] ==  A[(E[overlapping[I][2]], overlapping[I][3])])

  # But we must use Element explicitly
  solver.Add(
      solver.Element(A_flat, E[overlapping[I][0]] * word_len +
                     overlapping[I][1]) == solver
      .Element(A_flat, E[overlapping[I][2]] * word_len + overlapping[I][3]))

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

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

solver.NewSearch(db)
num_solutions = 0
while solver.NextSolution():
  print(E)
  print_solution(A, E, alpha, n, word_len)
  num_solutions += 1
solver.EndSearch()

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

def print_solution(A, E, alpha, n, word_len):
  for ee in range(n):
    print("%i: (%2i)" % (ee, E[ee].Value()), end=" ")
    print("".join(
        ["%s" % (alpha[A[ee, ii].Value()]) for ii in range(word_len)]))