1139-largest-1-bordered-square.adoc

1139. Largest 1-Bordered Square

{leetcode}/problems/largest-1-bordered-square/[LeetCode - Largest 1-Bordered Square^]

Given a 2D grid of 0`s and `1`s, return the number of elements in the largest square subgrid that has all `1`s on its border, or `0 if such a subgrid doesn’t exist in the grid.

Example 1:

Input: grid = [[1,1,1],[1,0,1],[1,1,1]]
Output: 9

Example 2:

Input: grid = [[1,1,0,0]]
Output: 1

Constraints:

• 1 ⇐ grid.length ⇐ 100

• 1 ⇐ grid[0].length ⇐ 100

• grid[i][j] is 0 or 1

link:{sourcedir}/_1139_Largest1BorderedSquare.java[role=include]