#4 most askedVery commonMediumTree BFS
Binary Tree Level Order Traversal
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🏢 Asked in real interviews
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[3, 9, 20, None, None, 15, 7] → [[3], [9, 20], [15, 7]]
🧪 Practice
Write your solution, then press Run tests. Explain your approach out loud as you go.
from collections import deque
def level_order(root):
pass
Output appears here. Press Run or Ctrl/⌘ + Enter.
Try it first. Struggling for a few minutes is how it sticks.