12_CountCompleteBinaryTree.py

# Question link - https://leetcode.com/problems/count-complete-tree-nodes/submissions/1745706208/?envType=study-plan-v2&envId=top-interview-150

# Definition for a binary tree node.
# class TreeNode:
#     def __init__(self, val=0, left=None, right=None):
#         self.val = val
#         self.left = left
#         self.right = right
class Solution:
    def countNodes(self, root: Optional[TreeNode]) -> int:
        # Base case : as the height .
        if root is None:
            return 0

        # height left subtree
        lh = self.findHeightofLeftTree(root)
        rh = self.fingHeightofrightTree(root)

        if lh == rh:
            return (1 << lh) - 1
        else:
            # Not equal at last level 
            return 1 + self.countNodes(root.left) + self.countNodes(root.right)

    def findHeightofLeftTree(self,node):
        height = 0
        while node:
            height += 1
            node = node.left
        return height

    def fingHeightofrightTree(self ,node):
        height = 0
        while node:
            height += 1
            node = node.right
        return height