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104. Maximum Depth of Binary Tree
Given a binary tree, find its maximum depth.
The maximum depth is the number of nodes along the longest path from the root node down to the farthest leaf node.
Note: A leaf is a node with no children.
Example:
Given binary tree [3,9,20,null,null,15,7],
3
/ \
9 20
/ \
15 7
return its depth = 3.
求一颗二叉树的最高深度，从根节点到叶子节点的最长路径长度。
class
Solution {
public:
int
maxDepth(TreeNode
* root) {
if (root
==
nullptr)
return
0;
return
max(
maxDepth(root->
left),
maxDepth(root->
right))
+
1;
}
};