先扫描二维矩阵，如果出现 0 元素，将首行对应列和首列对应行置 0，并记录首行和首列是否有自身出现过的 0 元素。然后将对应行和对应列置 0，再将首行和首列置0。
class Solution(object):
def setZeroes(self, matrix):
"""
:type matrix: List[List[int]]
:rtype: None Do not return anything, modify matrix in-place instead.
"""
m, n = len(matrix), len(matrix[0])
zero_row, zero_col = False, False
# 将首行和首列置为0，并标记最初首行和首列是否出现0元素
for i in range(m):
for j in range(n):
if matrix[i][j] == 0:
zero_row = True if i == 0 else zero_row
zero_col = True if j == 0 else zero_col
matrix[i][0] = matrix[0][j] = 0
# 将对应行置为0
for i in range(1, m):
if matrix[i][0] == 0:
for j in range(1, n):
matrix[i][j] = 0
# 将对应列置为0
for j in range(1, n):
if matrix[0][j] == 0:
for i in range(1, m):
matrix[i][j] = 0
# 首行置0
if zero_row:
for j in range(n):
matrix[0][j] = 0
# 首列置0
if zero_col:
for i in range(m):
matrix[i][0] = 0
