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backtracking.py
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backtracking.py
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class BackTracing:
def __init__(self, bo):
self.bo = bo
def solve(self):
find = self.find_empty()
if not find:
return True
else:
row, col = find
for i in range(1,10):
if self.valid(i, (row, col)):
self.bo[row][col] = i
if self.solve():
return True
self.bo[row][col] = 0
return False
def valid(self, num, pos):
# Check row
for i in range(len(self.bo[0])):
if self.bo[pos[0]][i] == num and pos[1] != i:
return False
# Check column
for i in range(len(self.bo)):
if self.bo[i][pos[1]] == num and pos[0] != i:
return False
# Check box
box_x = pos[1] // 3
box_y = pos[0] // 3
for i in range(box_y*3, box_y*3 + 3):
for j in range(box_x * 3, box_x*3 + 3):
if self.bo[i][j] == num and (i,j) != pos:
return False
return True
def print_board(self):
for i in range(len(self.bo)):
if i % 3 == 0 and i != 0:
print("- - - - - - - - - - - - - ")
for j in range(len(self.bo[0])):
if j % 3 == 0 and j != 0:
print(" | ", end="")
if j == 8:
print(self.bo[i][j])
else:
print(str(self.bo[i][j]) + " ", end="")
def find_empty(self):
for i in range(len(self.bo)):
for j in range(len(self.bo[0])):
if self.bo[i][j] == 0:
return (i, j) # row, col
return None