1、列表生成式
# 行
rows = [{} for i in range(9)]
# 列
columns = [{} for i in range(9)]
# 9个小格
boxes = [{} for i in range(9)]
2、python字典的get方法
dict.get(key, default=None)
如果key不存在,返回第二个参数,如果没有指定第二个参数,返回None
本题遍历一次,对象为所有的数独中的元素,判断不为.则判断是否重复出现在字典中
对于每一行,如果第一次出现这个数字,值记为1,第二次出现就加1,判断只要大于1,说明出现了两次
class Solution(object):
def isValidSudoku(self, board):
"""
:type board: List[List[str]]
:rtype: bool
"""
# 行
rows = [{} for i in range(9)]
# 列
columns = [{} for i in range(9)]
# 所有小格
boxes = [{} for i in range(9)]
for i in range(9):
for j in range(9):
num = board[i][j]
if num != '.':
num = int(num)
# 第几个box
box_index = (i // 3) * 3 + j // 3
# keep the current cell value
rows[i][num] = rows[i].get(num, 0) + 1
columns[j][num] = columns[j].get(num, 0) + 1
boxes[box_index][num] = boxes[box_index].get(num, 0) + 1
# check if this value has been already seen before
if rows[i][num] > 1 or columns[j][num] > 1 or boxes[box_index][num] > 1:
return False
return True
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"]
]
print(Solution().isValidSudoku(board))