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Maximum Depth Of Binary Tree
EasyVerifiedTreeBFSDFS~12 min
Given the root of a binary tree, return its maximum depth: the number of nodes along the longest path from root to a leaf.
A node is { val, left, right } with null children; the whole empty tree is null. The input arrives as the root node directly.
Examples
in{val:3, left:{val:9}, right:{val:20, left:{val:15}, right:{val:7}}}
out3
Longest root-to-leaf path 3 → 20 → 15 has 3 nodes.
innull
out0
An empty tree has depth 0.
Constraints
- 0 ≤ number of nodes ≤ 10⁴
- -100 ≤ node.val ≤ 100
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