Write a function that determines the minimum number of minutes required for all fresh oranges in a grid to become rotten. Every minute, any fresh orange that is 4-directionally adjacent (up, down, left, right) to a rotten orange also becomes rotten. If it is impossible to rot all fresh oranges, return -1.
Input: A 2D array grid representing the grid of oranges.
Each cell in the grid can be:
0 → an empty cell
1 → a fresh orange
2 → a rotten orange
Output: Return the minimum number of minutes it takes for all fresh oranges to become rotten. If it’s not possible, return -1.
// Example 1:
Input: [
[2,1,1],
[1,1,0],
[0,1,1]
]
Output: 4
// Example 2:
Input: [
[2,1,1],
[0,1,1],
[1,0,1]
]
Output: -1
// Example 3:
Input: [[0,2]]
Output: 0
Constraints & Edge Cases
The grid can be empty.
- There may be no fresh or no rotten oranges at the start.
- Rotten oranges spread the rot to adjacent fresh oranges in 4 directions: up, down, left, and right.
- If fresh oranges are blocked by empty cells and can’t be reached, return -1.
- If there are no fresh oranges initially, return 0.
- If all oranges are already rotten, return 0.
