> For the complete documentation index, see [llms.txt](https://docs-57.gitbook.io/data-structure-and-algorithms/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs-57.gitbook.io/data-structure-and-algorithms/problems/graph/rotting-oranges.md).

# Rotting Oranges

You are given an `m x n` `grid` where each cell can have one of three values:

* `0` representing an empty cell,
* `1` representing a fresh orange, or
* `2` representing a rotten orange.

Every minute, any fresh orange that is **4-directionally adjacent** to a rotten orange becomes rotten.

Return *the minimum number of minutes that must elapse until no cell has a fresh orange*. If *this is impossible, return* `-1`.

 

**Example 1:**

![](https://assets.leetcode.com/uploads/2019/02/16/oranges.png)

<pre><code><strong>Input: grid = [[2,1,1],[1,1,0],[0,1,1]]
</strong><strong>Output: 4
</strong></code></pre>

**Example 2:**

<pre><code><strong>Input: grid = [[2,1,1],[0,1,1],[1,0,1]]
</strong><strong>Output: -1
</strong><strong>Explanation: The orange in the bottom left corner (row 2, column 0) is never rotten, because rotting only happens 4-directionally.
</strong></code></pre>

**Example 3:**

<pre><code><strong>Input: grid = [[0,2]]
</strong><strong>Output: 0
</strong><strong>Explanation: Since there are already no fresh oranges at minute 0, the answer is just 0.
</strong></code></pre>

&#x20;

**Constraints:**

* `m == grid.length`
* `n == grid[i].length`
* `1 <= m, n <= 10`
* `grid[i][j]` is `0`, `1`, or `2`.

```csharp
public class Solution {
     public int OrangesRotting(int[][] grid)
    {
        int n = grid.Length;
        int m = grid[0].Length;
        int fresh = 0;
        Queue<(int, int)> queue = new Queue<(int, int)>();

        for (int i = 0; i < n; i++)
        {
            for (int j = 0; j < m; j++)
            {
                if (grid[i][j] == 2)
                {
                    queue.Enqueue((i, j));
                }
                else if (grid[i][j] == 1)
                {
                    fresh++;
                }
            }
        }

        if (fresh == 0)
            return 0;

        int level = 0;
        while (queue.Count > 0)
        {
            level++;
            int size = queue.Count;
            for (int i = 0; i < size; i++)
            {
                var (x, y) = queue.Dequeue();

                if (x - 1 >= 0 && grid[x - 1][y] == 1)
                {
                    queue.Enqueue((x - 1, y));
                    grid[x - 1][y] = 2;
                    fresh--;
                }
                if (x + 1 < n && grid[x + 1][y] == 1)
                {
                    queue.Enqueue((x + 1, y));
                    grid[x + 1][y] = 2;
                    fresh--;
                }
                if (y - 1 >= 0 && grid[x][y - 1] == 1)
                {
                    queue.Enqueue((x, y - 1));
                    grid[x][y - 1] = 2;
                    fresh--;
                }
                if (y + 1 < m && grid[x][y + 1] == 1)
                {
                    queue.Enqueue((x, y + 1));
                    grid[x][y + 1] = 2;
                    fresh--;
                }

            }

        }

        return fresh > 0 ? -1 : level-1;

    }
}
```


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