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, or2
representing a rotten orange.
Every minute, any fresh orange that is 4directionally 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:
0 1 2 3 4
2 1 1 2 2 1 2 2 2 2 2 2 2 2 2
1 1 0 => 2 1 0 => 2 2 0 => 2 2 0 => 2 2 0
0 1 1 0 1 1 0 1 1 0 2 1 0 2 2
Input: grid = [[2,1,1],[1,1,0],[0,1,1]]
Output: 4
Example 2:
Input: grid = [[2,1,1],[0,1,1],[1,0,1]]
Output: 1
Explanation: The orange in the bottom left corner (row 2, column 0) is never rotten,
because rotting only happens 4directionally.
Example 3:
Input: grid = [[0,2]]
Output: 0
Explanation: Since there are already no fresh oranges at minute 0,
the answer is just 0.
Constraints:
m == grid.length
n == grid[i].length
1 <= m, n <= 10
grid[i][j]
is0
,1
, or2
.

