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🔥Rotting Oranges: Multi-Source Grid Wavefront BFSMedium
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Rotting Oranges: Multi-Source Grid Wavefront BFS

Targeted in FAANG & Tech OA:AmazonUberSwiggy
Real-World Engineering Context
Used in epidemiology contagion spread models, wildfire propagation simulators, and cascading node failure alerts in AWS data center clusters.
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, or - `2` representing a 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 cell has a fresh orange. If this is impossible, return `-1`.

Sample Test Cases

Input: [[[2,1,1],[1,1,0],[0,1,1]]]
Expected: 4
Input: [[[2,1,1],[0,1,1],[1,0,1]]]
Expected: -1
Input: [[[0,2]]]
Expected: 0

Constraints

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