http://www.apache.org/licenses/LICENSE-2.0

%pip install ortools

import sys
from ortools.constraint_solver import pywrapcp

default_r = 8
default_c = 8
X = -1
default_game = [[2, 3, X, 2, 2, X, 2, 1], [X, X, 4, X, X, 4, X, 2],
                [X, X, X, X, X, X, 4, X], [X, 5, X, 6, X, X, X, 2],
                [2, X, X, X, 5, 5, X, 2], [1, 3, 4, X, X, X, 4, X],
                [0, 1, X, 4, X, X, X, 3], [0, 1, 2, X, 2, 3, X, 2]]


def main(game="", r="", c=""):

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

  #
  # data
  #

  # Set default problem
  if game == "":
    game = default_game
    r = default_r
    c = default_c
  else:
    print("rows:", r, " cols:", c)

  #
  # Default problem from "Some Minesweeper Configurations",page 3
  # (same as problem instance minesweeper_config3.txt)
  # It has 4 solutions
  #
  # r = 8
  # c = 8
  # X = -1
  # game = [
  #     [2,3,X,2,2,X,2,1],
  #     [X,X,4,X,X,4,X,2],
  #     [X,X,X,X,X,X,4,X],
  #     [X,5,X,6,X,X,X,2],
  #     [2,X,X,X,5,5,X,2],
  #     [1,3,4,X,X,X,4,X],
  #     [0,1,X,4,X,X,X,3],
  #     [0,1,2,X,2,3,X,2]
  #     ]

  S = [-1, 0, 1]  # for the neighbors of "this" cell

  # print problem instance
  print("Problem:")
  for i in range(r):
    for j in range(c):
      if game[i][j] == X:
        print("X", end=" ")
      else:
        print(game[i][j], end=" ")
    print()
  print()

  # declare variables
  mines = {}
  for i in range(r):
    for j in range(c):
      mines[(i, j)] = solver.IntVar(0, 1, "mines %i %i" % (i, j))

  #
  # constraints
  #
  for i in range(r):
    for j in range(c):
      if game[i][j] >= 0:
        solver.Add(mines[i, j] == 0)
        # this cell is the sum of all the surrounding cells
        solver.Add(game[i][j] == solver.Sum([
            mines[i + a, j + b]
            for a in S
            for b in S
            if i + a >= 0 and j + b >= 0 and i + a < r and j + b < c
        ]))
      if game[i][j] > X:
        # This cell cannot be a mine
        solver.Add(mines[i, j] == 0)

  #
  # solution and search
  #
  solution = solver.Assignment()
  solution.Add([mines[(i, j)] for i in range(r) for j in range(c)])

  collector = solver.AllSolutionCollector(solution)
  solver.Solve(
      solver.Phase([mines[(i, j)] for i in range(r) for j in range(c)],
                   solver.INT_VAR_SIMPLE, solver.ASSIGN_MIN_VALUE), [collector])

  num_solutions = collector.SolutionCount()
  print("num_solutions: ", num_solutions)
  if num_solutions > 0:
    for s in range(num_solutions):
      minesval = [
          collector.Value(s, mines[(i, j)]) for i in range(r) for j in range(c)
      ]
      for i in range(r):
        for j in range(c):
          print(minesval[i * c + j], end=" ")
        print()
      print()

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

  else:
    print("No solutions found")


#
# Read a problem instance from a file
#
def read_problem(file):
  f = open(file, "r")
  rows = int(f.readline())
  cols = int(f.readline())
  game = []
  for i in range(rows):
    x = f.readline()
    row = [0] * cols
    for j in range(cols):
      if x[j] == ".":
        tmp = -1
      else:
        tmp = int(x[j])
      row[j] = tmp
    game.append(row)
  return [game, rows, cols]


#
# Print the mines
#
def print_mines(mines, rows, cols):
  for i in range(rows):
    for j in range(cols):
      print(mines[i, j], end=" ")
    print("")


def print_game(game, rows, cols):
  for i in range(rows):
    for j in range(cols):
      print(game[i][j], end=" ")
    print("")


if len(sys.argv) > 1:
  file = sys.argv[1]
  print("Problem instance from", file)
  [game, rows, cols] = read_problem(file)
  # print_game(game, rows, cols)
  main(game, rows, cols)
else:
  main()