https://leetcode.com/problems/count-complete-tree-nodes


Runtime: 16 ms, faster than 88.64% of Go online submissions for Count Complete Tree Nodes.
Memory Usage: 7.4 MB, less than 96.97% of Go online submissions for Count Complete Tree Nodes.



```go
var counting = 0

func travel(node *TreeNode) {
    if node != nil {
        counting += 1
        travel(node.Left)
        travel(node.Right)
    }
}

func countNodes(root *TreeNode) int {
    //4:19
    counting = 0
    travel(root)
    return counting
    //4:20
}
```