# Bit-Manipulation count true trick

#### 2022-07-22 15:11

> ##### Algorithms:
>
> #algorithm #bit_manipulation
>
> ##### Data Structure:
>
> #DS #bitset
>
> ##### Difficulty:
>
> #CS_analysis #difficulty_easy
>
> ##### Additional tags:

##### Related problems:

### What is Bit-Manipulation count true trick?

(n & (n - 1))

### How does Bit-Manipulation count true trick work?

#### validate if the number is power of 2

See [[Leetcode Power-of-Two#Method 1 using masking]]

#### Counting 1

See [[Leetcode Number-of-1-Bits#Method 2 n n - 1 method]]