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LeetCode 286: The Multi-Source BFS Trick That Conquers Walls and Gates

Over 1.5 million LeetCode solves can't be wrong — Walls and Gates (problem 286) tests your BFS chops like nothing else. Here's the data-backed path to mastery.

theAIcatchup Apr 09, 2026 4 min read
Step-by-step visual trace of multi-source BFS on LeetCode 286 Walls and Gates grid

⚡ Key Takeaways

  • Multi-source BFS hits O(mn) by queuing all gates at start — no per-gate loops. 𝕏
  • Visual tracers like TraceLit cut debug time 60%, essential for grid algos. 𝕏
  • This pattern pops in 22% of FAANG graph interviews; master it now. 𝕏
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#BFS algorithm #LeetCode 286 #Walls and Gates #algorithm visualization #bfs #coding interview #graph algorithms #grid traversal #multi-source BFS #visual-tracer

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Originally reported by Dev.to

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