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SudokoSolver.py
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SudokoSolver.py
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class Point:
def __init__(self, x, y):
self.x = x
self.y = y
class Board:
def __init__(self, board):
self.board = board
self.dim = len(board)
self.free_count = 0
for i in range(self.dim):
for j in range(self.dim):
if self.isempty(i, j):
self.free_count += 1
self.move = [None] * 81
def fill_square(self, pos, val):
self.board[pos.x][pos.y] = val
self.free_count -= 1
def free_square(self, pos):
self.board[pos.x][pos.y] = 0
self.free_count += 1
def next_square(self):
next_pos = None
for i in range(self.dim):
for j in range(self.dim):
if self.isempty(i, j):
pos_vals = set([i for i in range(1, 10)])
for k in range(self.dim):
if not self.isempty(i, k):
pos_vals.discard(self.board[i][k])
if not self.isempty(k, j):
pos_vals.discard(self.board[k][j])
ith_sec = i - i % 3
jth_sec = j - j % 3
for a in range(ith_sec, ith_sec + 3):
for b in range(jth_sec, jth_sec + 3):
if not self.isempty(a, b):
pos_vals.discard(self.board[a][b])
if next_pos is None or len(next_pos[2]) > len(pos_vals):
next_pos = (i, j, pos_vals)
if len(next_pos[2]) == 0:
return -1, -1, None
return next_pos
def isempty(self, i, j):
return self.board[i][j] == 0
def write(self, file):
stng = self.__str__()
with open(file, 'w') as out:
out.write(stng)
def __str__(self):
stng = ""
for i in range(self.dim):
if i % 3 == 0:
stng += '-' * 19 + '\n'
for j in range(self.dim):
if j % 3 == 0:
stng += '|'
stng += str(self.board[i][j])
if (j + 1) % 3 != 0:
stng += ' '
stng += '|\n'
stng += '-' * 19 + '\n'
return stng
finished = False
def construct_cand(a, k, board):
x, y, possible = board.next_square()
board.move[k] = Point(x, y)
ncand = 0
c = []
if x < 0 and y < 0:
return c, ncand
for i in possible:
c.append(i)
ncand += 1
return c, ncand
def make_move(a, k, board):
board.fill_square(board.move[k], a[k])
def unmake_move(a, k, board):
board.free_square(board.move[k])
def is_a_soln(a, k, board):
if board.free_count == 0:
return True
else:
return False
def process_soln(a, k, board):
board.write('output.txt')
finished = True
def backtrack(a, k, inp):
global finished
if is_a_soln(a, k, inp):
process_soln(a, k, inp)
else:
k += 1
c, ncand = construct_cand(a, k, inp)
for i in range(ncand):
a[k] = c[i]
make_move(a, k, inp)
backtrack(a, k, inp)
unmake_move(a, k, inp)
if finished:
return
def main():
with open("input.txt") as inp:
board = []
for i in range(9):
board.append(list(map(int, inp.readline().split())))
board = Board(board)
a = [None] * 81
backtrack(a, 0, board)
if __name__ == '__main__':
main()