# 231. Power of Two

Given an integer `n`, return `true` if it is a power of two. Otherwise, return `false`.

An integer `n` is a power of two, if there exists an integer `x` such that `n == 2x`.

Example 1:

`Input: n = 1Output: trueExplanation: 20 = 1`

Example 2:

`Input: n = 16Output: trueExplanation: 24 = 16`

Example 3:

`Input: n = 3Output: false`

Constraints:

• `-231 <= n <= 231 - 1`

Follow up: Could you solve it without loops/recursion?

# 191. Number of 1 Bits

Write a function that takes an unsigned integer and returns the number of ‘1’ bits it has (also known as the Hamming weight).

Note:

• Note that in some languages, such as Java, there is no unsigned integer type. In this case, the input will be given as a signed integer type. It should not affect your implementation, as the integer’s internal binary representation is the same, whether it is signed or unsigned.
• In Java, the compiler represents the signed integers using 2’s complement notation. Therefore, in Example 3, the input represents the signed integer. `-3`.

Example 1:

`Input: n = 00000000000000000000000000001011Output: 3Explanation: The input binary string 00000000000000000000000000001011 has a total of three '1' bits.`

Example 2:

`Input: n = 00000000000000000000000010000000Output: 1Explanation: The input binary string 00000000000000000000000010000000 has a total of one '1' bit.`

Example 3:

`Input: n = 11111111111111111111111111111101Output: 31Explanation: The input binary string 11111111111111111111111111111101 has a total of thirty one '1' bits.`

Constraints:

• The input must be a binary string of length `32`.

Follow up: If this function is called many times, how would you optimize it?

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## More from Joo Hee Paige Kim

Consistency achieves everything https://github.com/paigekim29

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## Joo Hee Paige Kim

Consistency achieves everything https://github.com/paigekim29