Network disconnection
Description
Suppose that there is a table (board) consisting of 1s and 0s. A space in the table is shaped as a 1 x 1 square. Write a function solution
to find the largest square consisting of 1s in the table and return its size (The square must be parallel to the axis).
For example, assume that a table is given as follows.
1  2  3  4 

0  1  1  1 
1  1  1  1 
1  1  1  1 
0  0  1  0 
Then, the largest square is as follows.
1  2  3  4 

0  1 
1 
1 
1  1 
1 
1 
1  1 
1 
1 
0  0  1  0 
Since its size is 9, return 9.
Constraints
 Table (board) is given as a 2dimensional array.
 Length of row of table (board) : natural number less than 1,000.
 Length of column of table (board) : natural number less than 1,000.
 Table (board) consists of only 1 and 0.
Examples
board  answer 

[[0,1,1,1],[1,1,1,1],[1,1,1,1],[0,0,1,0]]  9 
[[0,0,1,1],[1,1,1,1]]  4 
Example #1
It is the same as the example in the problem statement.
Example #2
The largest square is as follows.
 0  0  1
 1

 1  1  1
 1

Since its size is 4, return 4.
Result
Stop
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