# 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:**

![](https://assets.leetcode.com/uploads/2019/05/03/1336_ex1.JPG)

```
**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:**

![](https://assets.leetcode.com/uploads/2019/05/03/1336_ex2.JPG)

```
**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

```java
```