Maximum Depth of Binary Tree (104) from https://leetcode.com/problems/maximum-depth-of-binary-tree/description/

maxdepth.go

func maxDepth(root *TreeNode) int {
  	if root == nil {
		return 0
	}
	d := 1 + max(maxDepth(root.Right), maxDepth(root.Left))
	return d  
}

func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}