/**
* Definition for a binary tree node.
* type TreeNode struct {
* Val int
* Left *TreeNode
* Right *TreeNode
* }
*/
func Max(a, b int) int {
if a >= b {
return a
}else {
return b
}
}
func maxDepth(root *TreeNode) int {
if nil == root {
return 0
}
letfLevel := maxDepth(root.Left)
rightLevel := maxDepth(root.Right)
return Max(letfLevel, rightLevel) + 1
}