<p>You are given an <code>m x n</code> <code>grid</code> where each cell can have one of three values:</p>

<ul>
	<li><code>0</code> representing an empty cell,</li>
	<li><code>1</code> representing a fresh orange, or</li>
	<li><code>2</code> representing a rotten orange.</li>
</ul>

<p>Every minute, any fresh orange that is <strong>4-directionally adjacent</strong> to a rotten orange becomes rotten.</p>

<p>Return <em>the minimum number of minutes that must elapse until no cell has a fresh orange</em>. If <em>this is impossible, return</em> <code>-1</code>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2019/02/16/oranges.png" style="width: 650px; height: 137px;" />
<pre>
<strong>Input:</strong> grid = [[2,1,1],[1,1,0],[0,1,1]]
<strong>Output:</strong> 4
</pre>

<p><strong class="example">Example 2:</strong></p>

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

<p><strong class="example">Example 3:</strong></p>

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

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>m == grid.length</code></li>
	<li><code>n == grid[i].length</code></li>
	<li><code>1 &lt;= m, n &lt;= 10</code></li>
	<li><code>grid[i][j]</code> is <code>0</code>, <code>1</code>, or <code>2</code>.</li>
</ul>

class Solution {
public:
    int orangesRotting(vector<vector<int>>& grid) {
        int days = 0;
        vector<vector<int>> rottenQueue;
        int rows = grid.size();
        int cols = grid[0].size();
        int i = 0, j = 0;

        while (i < rows) {
            j = 0;
            while (j < cols) {
                if (grid[i][j] == 2)
                    rottenQueue.push_back({i, j});
                j++;
            }
            i++;
        }
        
        while (!rottenQueue.empty()) {
            days++;
            vector<vector<int>> tempQueue = rottenQueue;
            rottenQueue.clear();

            while (!tempQueue.empty()) {
                int x = tempQueue[0][0];
                int y = tempQueue[0][1];
                tempQueue.erase(tempQueue.begin());

                switch (x - 1 >= 0 && grid[x - 1][y] == 1) {
                    case true:
                        grid[x - 1][y] = 2;
                        rottenQueue.push_back({x - 1, y});
                        break;
                }
                switch (x + 1 < rows && grid[x + 1][y] == 1) {
                    case true:
                        grid[x + 1][y] = 2;
                        rottenQueue.push_back({x + 1, y});
                        break;
                }
                switch (y - 1 >= 0 && grid[x][y - 1] == 1) {
                    case true:
                        grid[x][y - 1] = 2;
                        rottenQueue.push_back({x, y - 1});
                        break;
                }
                switch (y + 1 < cols && grid[x][y + 1] == 1) {
                    case true:
                        grid[x][y + 1] = 2;
                        rottenQueue.push_back({x, y + 1});
                        break;
                }
            }
        }

        i = 0;
        while (i < rows) {
            j = 0;
            while (j < cols) {
                if (grid[i][j] == 1)
                    return -1;
                j++;
            }
            i++;
        }

        if (days == 0)
            return 0;
        return days - 1;   
    }
};
17500