12月亚麻OA1

1. example input:
input:
row: 4:
columns = 5
grid:
[[0,1,1,0,1],
[0,1,0,1,0],
[0,0,0,0,1],
[0,1,0,0,0]]

output: 2

explanation:
at the end of first hour:
1,1,1,1,1
1,1,1,1,1
0,1,0,1,1
1,1,1,0,1

at the end of 2 hour:
1,1,1,1,1
1,1,1,1,1
1,1,1,1,1
1,1,1,1,1

2. testcase1
input: 4, 4
[[1,1,0,0],
[0,0,0,0],
[0,0,1,1],
[0,0,0,0]]

expected return value:
2

testcase 2:
input: 7, 7
[
[1,0,0,0,0,0,0],
[0,1,0,0,0,0,0],
[0,0,1,0,0,0,0],
[0,0,0,1,0,0,0],
[0,0,0,0,1,0,0],
[0,0,0,0,0,1,0],
[0,0,0,0,0,0,1]
]