# Copyright 2010 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.

"""

  Hidato puzzle in Google CP Solver.

  http://www.shockwave.com/gamelanding/hidato.jsp
  http://www.hidato.com/
  '''
  Puzzles start semi-filled with numbered tiles.
  The first and last numbers are circled.
  Connect the numbers together to win. Consecutive
  number must touch horizontally, vertically, or
  diagonally.
  '''

  The following note was added by Hakan Kjellerstrand:
  This model was written by Laurent Perron, and
  is a great improvement of my own version:
  http://www.hakank.org/google_or_tools/hidato.py
 
"""

from ortools.constraint_solver import pywrapcp

def BuildTuples(r, c):
  results = []
  for x in range(r):
    for y in range(c):
      for dx in (-1, 0, 1):
        for dy in (-1, 0, 1):
          if (x + dx >= 0 and
              x + dx < r and
              y + dy >= 0 and
              y + dy < c and
              (dx != 0 or dy != 0)):
            results.append((x * c + y, (x + dx) * c + (y + dy)))
  return results

def main():

  # Create the solver.
  solver = pywrapcp.Solver('n-queens')

  #
  # data
  #
  #
  # Simple problem
  #
  # r = 3
  # c = r
  # puzzle = [
  #     [6,0,9],
  #     [0,2,8],
  #     [1,0,0]
  #     ]


  #     r = 7
  #     c = 7
  #     puzzle =  [
  #         [0,44,41, 0, 0, 0, 0],
  #         [0,43, 0,28,29, 0, 0],
  #         [0, 1, 0, 0, 0,33, 0],
  #         [0, 2,25, 4,34, 0,36],
  #         [49,16, 0,23, 0, 0, 0],
  #         [0,19, 0, 0,12, 7, 0],
  #         [0, 0, 0,14, 0, 0, 0]
  #         ]


  # Problems from the book:
  # Gyora Bededek: "Hidato: 2000 Pure Logic Puzzles"

  # Problem 1 (Practice)
  # r = 5
  # c = r
  # puzzle = [
  #    [ 0, 0,20, 0, 0],
  #    [ 0, 0, 0,16,18],
  #    [22, 0,15, 0, 0],
  #    [23, 0, 1,14,11],
  #    [ 0,25, 0, 0,12],
  #    ]


#     # problem 2 (Practice)
#  r = 5
#  c = r
#  puzzle= [
#      [0, 0, 0, 0,14],
#      [0,18,12, 0, 0],
#      [0, 0,17, 4, 5],
#      [0, 0, 7, 0, 0],
#      [9, 8,25, 1, 0],
#      ];

  # problem 3 (Beginner)
  #     r = 6
  #     c = r
  #     puzzle =  [
  #         [ 0, 26,0, 0, 0,18],
  #         [ 0, 0,27, 0, 0,19],
  #         [31,23, 0, 0,14, 0],
  #         [ 0,33, 8, 0,15, 1],
  #         [ 0, 0, 0, 5, 0, 0],
  #         [35,36, 0,10, 0, 0]
  #         ];


  # Problem 15 (Intermediate)
  # Note: This takes very long time to solve...
  r = 8
  c = r
  puzzle = [
      [64, 0, 0, 0, 0, 0, 0, 0],
      [ 1,63, 0,59,15,57,53, 0],
      [ 0, 4, 0,14, 0, 0, 0, 0],
      [ 3, 0,11, 0,20,19, 0,50],
      [ 0, 0, 0, 0,22, 0,48,40],
      [ 9, 0, 0,32,23, 0, 0,41],
      [27, 0, 0, 0,36, 0,46, 0],
      [28,30, 0,35, 0, 0, 0, 0]
      ]

  print_game(puzzle, r, c)

  #
  # declare variables
  #
  positions = [solver.IntVar(0, r * c - 1, 'p of %i' % i) for i in range(r * c)]

  #
  # constraints
  #
  solver.Add(solver.AllDifferent(positions, True))

  #
  # Fill in the clues
  #
  for i in range(r):
    for j in range(c):
      if puzzle[i][j] > 0:
        solver.Add(positions[puzzle[i][j] - 1] == i * c + j)

  # Positions are closed another. Use a table.
  close_tuples = BuildTuples(r, c)
  for k in range(1, r * c - 1):
    solver.Add(solver.AllowedAssignments((positions[k], positions[k + 1]),
                                         close_tuples))

  #
  # solution and search
  #

  # db: DecisionBuilder
  db = solver.Phase(positions,
                    solver.CHOOSE_MIN_SIZE_LOWEST_MIN,
                    solver.ASSIGN_MIN_VALUE)

  solver.NewSearch(db)
  num_solutions = 0
  while solver.NextSolution():
    num_solutions += 1
    print_board(positions, r, c, num_solutions)
    print

  solver.EndSearch()

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


def print_board(positions, rows, cols, num_solution):
  print 'Solution %i:' % num_solution
  for i in range(rows):
    for j in range(cols):
      index = i * rows + j
      for k in range(rows * cols):
        if positions[k].Value() == index:
          print "% 2s" % (k + 1),
    print ''

def print_game(game, rows, cols):
  print 'Initial game (%i x %i)' % (rows, cols)
  for i in range(rows):
    for j in range(cols):
      print "% 2s" % game[i][j],
    print ''
  print



if __name__ == '__main__':
    main()