Power of Two

easyPRODynamic Programming & MathLinkedIn DSA

Given an integer n, return True if it is a power of two.

Example

Input

Output

True

Reasoning

Input: n is a single integer, here 16. It can be any 32-bit signed value, so zero and negative numbers are valid inputs too.
The math: n is a power of two when $n = 2^k$ for some whole number $k \ge 0$ . For the sample, $16 = 2 \times 2 \times 2 \times 2 = 2^4$ , so $k = 4$ and the answer is True.
Contrast: $12 = 2^2 \times 3$ is not, because its factorisation contains an odd factor other than $1$ . Likewise $3$ sits between $2^1 = 2$ and $2^2 = 4$ , which gives False.
Edges to notice: $1 = 2^0$ counts, so 1 gives True. Every $2^k$ is strictly positive, so $0$ and all negative inputs (even $-16$ ) give False.
Output: a single boolean, True for the sample. Notice that the powers of two thin out fast: there are only 31 of them in the whole input range, from $2^0$ up to $2^{30}$ .

Constraints

-2^31 <= n <= 2^31 - 1

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solution.py

Python 3.13

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Power of Two

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