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sudoku_solver.py
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sudoku_solver.py
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"""
https://leetcode.com/problems/sudoku-solver/
"""
import time
from typing import List
check_map = {
"1": False,
"2": False,
"3": False,
"4": False,
"5": False,
"6": False,
"7": False,
"8": False,
"9": False,
}
class Solution2:
def isValidSudoku(self, board: List[List[str]]) -> bool:
# Check rows
for row in board:
cm = check_map.copy()
for val in row:
if val == ".":
continue
if cm[val]:
return False
cm[val] = True
# Check columns
for i in range(len(board[0])):
cm = check_map.copy()
for b in board:
if b[i] == ".":
continue
if cm[b[i]]:
return False
cm[b[i]] = True
# Check sub-boxes
for i in range(0, 9, 3):
for j in range(0, 9, 3):
cm = check_map.copy()
for a in range(i, i + 3):
for b in range(j, j + 3):
if board[a][b] == ".":
continue
if cm[board[a][b]]:
return False
cm[board[a][b]] = True
return True
class PencilBoard:
def __init__(self) -> None:
self.map = {
"1": False,
"2": False,
"3": False,
"4": False,
"5": False,
"6": False,
"7": False,
"8": False,
"9": False,
}
self.is_value_provided = False
class Sudoku:
def __init__(self, board):
self.board = board
self.pencil_board = [[PencilBoard() * 9] * 9]
def is_possible(self, num: str, row_num, col_num) -> bool:
"""We check if a number in certain position is possible or not
Args:
num (str): _description_
row_num (_type_): _description_
col_num (_type_): _description_
Returns:
bool: _description_
"""
# check row
row = self.board[row_num]
for val in row:
if val == num:
return False
# check column
for b in self.board:
if b[col_num] == num:
return False
# check sub-boxes
i = (row_num % 3) * 3
j = (col_num % 3) * 3
for a in range(i, i + 3):
for b in range(j, j + 3):
if board[a][b] == num:
return False
return True
def init_fast_pencil(self):
for i in range(len(board)):
for j in range(len(board[i])):
if board[i][j] == ".":
for k, v in self.pencil_board[i][j].map.items():
if not v:
if self.is_possible(k, i, j):
self.pencil_board[i][j].map[k] = True
else:
self.pencil_board[i][j].is_value_provided = True
def update_fast_pencil(self):
"""Update pencil board based on new value update"""
pass
nums = {"1", "2", "3", "4", "5", "6", "7", "8", "9"}
class Solution:
def solveSudoku(self, board: List[List[str]]) -> None:
"""
Do not return anything, modify board in-place instead.
"""
all_filled = False
atleast_one_filled = False
while (not all_filled or not atleast_one_filled):
print(board)
atleast_one_filled = False
all_filled = True
for i, row in enumerate(board):
for j, val in enumerate(row):
# print(board[i][j])
if board[i][j] == ".":
all_filled = False
rn = self.checkRow(board, i)
cn = self.checkCol(board, j)
gn = self.checkGrid(board, i, j)
ln = rn.intersection(cn).intersection(gn)
if len(ln) == 1:
atleast_one_filled = True
print(ln)
board[i][j] = ln.pop()
time.sleep(1)
def checkRow(self, board, rowNum):
local_nums = nums.copy()
for n in board[rowNum]:
if n in local_nums:
local_nums.remove(n)
return local_nums
def checkCol(self, board, colNum):
local_nums = nums.copy()
for b in board:
if b[colNum] in local_nums:
local_nums.remove(b[colNum])
return local_nums
def checkGrid(self, board, rowNum, colNum):
local_nums = nums.copy()
grid_row_start = int(rowNum / 3) * 3
grid_col_start = int(colNum / 3) * 3
for i in range(grid_row_start, grid_row_start + 3):
for j in range(grid_col_start, grid_col_start + 3):
if board[i][j] in local_nums:
local_nums.remove(board[i][j])
return local_nums
def print_sudoku_board(board: List[List[str]]) -> None:
for b in board:
print(" ".join(b))
if __name__ == "__main__":
board = [
["5", "3", ".", ".", "7", ".", ".", ".", "."],
["6", ".", ".", "1", "9", "5", ".", ".", "."],
[".", "9", "8", ".", ".", ".", ".", "6", "."],
["8", ".", ".", ".", "6", ".", ".", ".", "3"],
["4", ".", ".", "8", ".", "3", ".", ".", "1"],
["7", ".", ".", ".", "2", ".", ".", ".", "6"],
[".", "6", ".", ".", ".", ".", "2", "8", "."],
[".", ".", ".", "4", "1", "9", ".", ".", "5"],
[".", ".", ".", ".", "8", ".", ".", "7", "9"],
]
board = [
[".", ".", "9", "7", "4", "8", ".", ".", "."],
["7", ".", ".", ".", ".", ".", ".", ".", "."],
[".", "2", ".", "1", ".", "9", ".", ".", "."],
[".", ".", "7", ".", ".", ".", "2", "4", "."],
[".", "6", "4", ".", "1", ".", "5", "9", "."],
[".", "9", "8", ".", ".", ".", "3", ".", "."],
[".", ".", ".", "8", ".", "3", ".", "2", "."],
[".", ".", ".", ".", ".", ".", ".", ".", "6"],
[".", ".", ".", "2", "7", "5", "9", ".", "."],
]
Solution().solveSudoku(board=board)
print_sudoku_board(board)