Count Complete Tree Nodes


#1

Given a complete binary tree, count the number of nodes.

Note:

Definition of a complete binary tree from Wikipedia:
In a complete binary tree every level, except possibly the last, is completely filled, and all nodes in the last level are as far left as possible. It can have between 1 and 2h nodes inclusive at the last level h.

Example:

Input: 
    1
   / \
  2   3
 / \  /
4  5 6

Output: 6

#2

The below algorithm uses a simple recursion and counts each node in a given binary tree.

func countNodes(root *TreeNode) int {
   var count int
    helper(root, &count)
    return count
}

func helper(root *TreeNode, count *int){
    if root==nil{
        return
    }
    helper(root.Left, count)
    helper(root.Right, count)
    *count++
}