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
class Solution:
def countNodes(self, root: TreeNode) -> int:
if not root:
return 0
rd = self.height(root.right)
ld = self.height(root.left)
if rd == ld:
return pow(2, ld) + self.countNodes(root.right)
else:
return pow(2, rd) + self.countNodes(root.left)
def height(self, root):
if not root:
return 0
return 1 + self.height(root.left)