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0036. Valid Sudoku
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0036. Valid Sudoku
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'''Determine if a 9 x 9 Sudoku board is valid. Only the filled cells need to be validated according to the following rules:
Each row must contain the digits 1-9 without repetition.
Each column must contain the digits 1-9 without repetition.
Each of the nine 3 x 3 sub-boxes of the grid must contain the digits 1-9 without repetition.
Note:
A Sudoku board (partially filled) could be valid but is not necessarily solvable.
Only the filled cells need to be validated according to the mentioned rules.
Example 1:
Input: 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"]]
Output: true
Example 2:
Input: board =
[["8","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"]]
Output: false
Explanation: Same as Example 1, except with the 5 in the top left corner being modified to 8. Since there are two 8's in the top left 3x3 sub-box, it is invalid.
Constraints:
board.length == 9
board[i].length == 9
board[i][j] is a digit 1-9 or '.'.
'''
class Solution:
def isValidSudoku(self, board: List[List[str]]) -> bool:
seen = set()
for i, row in enumerate(board): # iterate row
for j, val in enumerate(row): # iterate col
if val != ".":
# tuple (val,i) row出现过,以此类推,三种记录方式代表行列宫三个check
if (val, i) in seen or (j, val) in seen or (i//3, j//3, val) in seen:
return False
else:
seen.add((val, i))
seen.add((j, val))
seen.add((i//3, j//3, val))
print(seen)
return True
# row = [set() for _ in range(9)]
# col = [set() for _ in range(9)]
# box = [set() for _ in range(9)]
# for r in range(9):
# for c in range(9):
# val = board[r][c]
# # Check if the position is filled with number
# if val == ".":
# continue
# # Check the row
# if val in row[r]:
# return False
# row[r].add(val)
# # Check the column
# if val in col[c]:
# return False
# col[c].add(val)
# # Check the box
# i = (r//3) * 3 + c//3
# if val in box[i]:
# return False
# box[i].add(val)
# return True