About This Pattern
Master the Multi-source BFS pattern by practicing these problems organized by difficulty.Focus on the Key Signals - these are the indicators that tell you when to use this pattern.
Medium (2)
Walls And Gates
Fill distances to nearest gate in a 2D grid with rooms, walls, and gates.
Key Signals:
Start BFS from all gatesUpdate distancesQueue all sources
Rotting Oranges
Find minimum time for all oranges to rot (rot spreads to adjacent oranges each minute).
Key Signals:
BFS from all rottenTrack time levelsCount fresh oranges