ss_sudoku.py

from constraint import *


# board = [
#     "1  | 48|   ",
#     "  6|   |831",
#     "   |  5| 6 ",
# # -
#     "  5|   |7 9",
#     "   |5 7|   ",
#     "6 8|   |1  ",
# # -
#     " 3 |7  |   ",
#     "567|   |9  ",
#     "   |42 |  5"]

# board = [
#     "   |   |   ",
#     "   |   |   ",
#     "   |   |   ",
# # -
#     "   |   |   ",
#     " 5 |   |   ",
#     "   |   |   ",
# # -
#     "  2|   |   ",
#     "   |   |   ",
#     "   |7  |  3"]

board = [
    "   |   |   ",
    "   |   |   ",
    "   |   |   ",
# -
    "   |   |   ",
    "   |   |   ",
    "   |   |   ",
# -
    "   |   |   ",
    "   |   |   ",
    "   |   |   "]

# a string with 81 chars:
board2 = "".join([row.replace("|", "") for row in board])

def print_board(b):
    print("-------------")
    for i in range(9):
        for j in range(9):
            print(b[i*9 + j], end="")
        print()
    print()

problem = Problem()

# 81 variables, each 1-9
for i in range(81):
    if board2[i] == " ":
        # Unknown:
        problem.addVariable(i, range(1,10))
    else:
        v = int(board2[i])
        problem.addVariable(i,[v])

# Add constant single values, useful for siteswap calculations
# cause otherwise stupid bs happens
for i in range(9):
    problem.addVariable(100+i, [i])


# Make sure the variables in coords array form a valid siteswap.
def add_siteswap_const(coords):
    # indices to add constraint to in the given array
    for i1 in range(9):
        for i2 in range(i1+1, 9):
            # Add constraint to variables at index coords[i1] and coords[i2]...
            # The difference in these must not equal their distance in the siteswap,
            # mod 9 or something.
            problem.addConstraint(lambda a, b, diff: (a-b) % 9 != diff,
                                  (coords[i1], coords[i2], 100+i2-i1))


for j in range(9):
    # columns different
    problem.addConstraint(AllDifferentConstraint(), range(j*9, (j+1)*9))
    # colums are sss
    add_siteswap_const([i for i in range(j*9, (j+1)*9)])
    # rows different
    problem.addConstraint(AllDifferentConstraint(), range(j, 81, 9))
    # rows are sss
    add_siteswap_const([i for i in range(j, 81, 9)])

# boxes different
for i_b in range(0, 9, 3):
    for j_b in range(0, 9, 3):
        # uhh, now we've the top left corner of a box...
        # All the coords of squares in that box:
        vals = [d + i_b*9 + j_b for d in [0,1,2, 9,10,11, 18,19,20]]
        problem.addConstraint(AllDifferentConstraint(), vals)

i = 0
for sol in problem.getSolutionIter():
    i += 1
    if i % 100 == 0:
        print(i)
        print_board(sol)
# print_board(problem.getSolution())