Largest 1-Bordered Square
Given a 2D grid of 0s and 1s, return the number of elements in the largest square subgrid that has all 1s on its border, or 0 if such a subgrid does not exist in the grid.
Example 1
1 1 1 1 0 1 1 1 1
Input
grid = [[1,1,1],[1,0,1],[1,1,1]]Output
9The entire 3 by 3 grid has all 1s on its border, so its area is 9.
Example 2
1 1 0 0
Input
grid = [[1,1,0,0]]Output
1The largest square subgrid with a border of 1s is any single cell containing 1, so its area is 1.
Constraints
- 1 <= grid.length <= 100
- 1 <= grid[0].length <= 100
- grid[i][j] is 0 or 1