Multi-source

2 articles

dsa10 min read

Walls and Gates — Multi-Source BFS Every FAANG Grid Interview Tests

LC 286 Walls and Gates asks you to fill each empty room with its distance to the nearest gate. The key insight is to flip the direction: instead of BFS from every room, do multi-source BFS from all gates simultaneously and push distances outward in O(m*n) time.

March 19, 2026Read →

dsa7 min read

Walls and Gates — Multi-Source BFS Queue from Every Gate at Once

Solve LeetCode 286 Walls and Gates with multi-source BFS from every gate using a deque queue in O(m times n). A FAANG grid traversal classic.

March 19, 2026Read →