Rotting Oranges

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

• 0 - empty cell
• 1 - fresh orange
• 2 - 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 fresh oranges remain. If it is impossible, return -1.

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Example 1

grid = [
  [2, 1, 1],
  [1, 1, 0],
  [0, 1, 1]
]

Input: grid above
Output: 4
Explanation: The single rotten orange spreads minute by minute until all reachable fresh oranges are rotten after 4 minutes.

Example 2

grid = [
  [2, 1, 1],
  [0, 1, 1],
  [1, 0, 1]
]

Input: grid above
Output: -1
Explanation: The orange in the bottom-left corner is cut off by empty cells and can never be reached.

Example 3

Input: grid = [[0, 2]]
Output: 0
Explanation: There are no fresh oranges, so no time is needed.

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Constraints

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