Given an integer i. Print the maximum number of nodes on level i of a binary tree.
Example 1:
Input: 5
Output: 16
Example 2:
Input: 1
Output: 1

Your Task:
Complete the function countNode() which takes an integer i as input and prints the count of maximum number of nodes at that level.

Expected Time Complexity: O(1)
Expected Space Complexity: O(1)

Constraints:
1<=i<=20

见题面

见题面