Rotting Oranges

# Rotting Oranges Implement `minutes_until_all_rotten(grid: list[list[int]]) -> int`. The grid contains `0` for an empty cell, `1` for a fresh orange, and `2` for a rotten orange. Each minute, every fresh orange directly above, below, left, or right of a rotten orange becomes rotten. Return the minimum number of minutes until no fresh orange remains, or `-1` if that is impossible. ### Input Domain - `1 <= rows, columns <= 100`. - Every cell is `0`, `1`, or `2`. - Rotting within one minute happens simultaneously. ### Output Rules - Return `0` when there are no fresh oranges initially. - Return `-1` when at least one fresh orange can never be reached. - Return one integer, so tie semantics are not applicable. ### Constraints - Target time complexity is `O(rows * columns)`. - Additional space may be `O(rows * columns)`. ### Examples #### Example 1 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` ```hint Start all sources together The minute count is shortest-path distance from the nearest initially rotten orange, so initialize the frontier with every rotten cell. ```