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Count Complete Tree Nodes

Given the root of a complete binary tree (as a level-order array), return the number of nodes.

A complete binary tree has every level fully filled except possibly the last, which is filled from left to right.

Input:

1,2,3,4,5,6

Output:

Reasoning:

The input array 1,2,3,4,5,6 represents a level-order traversal of the complete binary tree.
We can visualize the tree as:
- Level 1: 1
- Level 2: 2, 3
- Level 3: 4, 5, 6
Since it's a complete binary tree, every level is fully filled except possibly the last, which is filled from left to right.
The number of nodes is equal to the number of elements in the input array, so the output is $6$ .

Editor

Python 3.13.1

0/0

Run code to see test results.

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