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.
/**
* Definition for a binary tree node.
* type TreeNode struct {
* Val int
* Left *TreeNode
* Right *TreeNode
* }
*/
func maxDepth(root *TreeNode) int {
if root == nil {
return 0
}
return maxDepthCore(root)
}
func maxDepthCore(root *TreeNode) int {
if root == nil {
return 0
}
res := 1
hleft := maxDepthCore(root.Left)
hright := maxDepthCore(root.Right)
if hleft > hright {
res += hleft
} else {
res += hright
}
return res
}