1162. As Far from Land as Possible

https://leetcode.com/problems/as-far-from-land-as-possible

Description

Given an n x n grid containing only values 0 and 1, where 0 represents water and 1 represents land, find a water cell such that its distance to the nearest land cell is maximized, and return the distance. If no land or water exists in the grid, return -1.

The distance used in this problem is the Manhattan distance: the distance between two cells (x0, y0) and (x1, y1) is |x0 - x1| + |y0 - y1|.

Example 1:

**Input:** grid = [[1,0,1],[0,0,0],[1,0,1]]
**Output:** 2
**Explanation:** The cell (1, 1) is as far as possible from all the land with distance 2.

Example 2:

**Input:** grid = [[1,0,0],[0,0,0],[0,0,0]]
**Output:** 4
**Explanation:** The cell (2, 2) is as far as possible from all the land with distance 4.

Constraints:

• n == grid.length

• n == grid[i].length

• 1 <= n <= 100

• grid[i][j] is 0 or 1

ac