The ultimate guide to bit manipulation for coding interviews. Developed by FAANG engineers, practice with real-world interview questions, and get interview-ready in just a few hours.

This course teaches bit manipulation, a powerful technique to enhance algorithmic and problem-solving skills. It is a critical topic for those preparing for coding interviews for top tech companies, startups and industry leaders. Competitive programmers can take full advantage of this course by running most of the bit-related problems in O(1) complexity.

The course will begin by educating you about the number system and its representation, decimal and binary, followed by the six bitwise operators: AND, OR, NOT, XOR, and bit-shifting (left, right).

You will receive ample practical experience working through practice problems to improve your comprehension.

Upon completing this course, you will be able to solve problems with greater efficiency and speed.

Grokking Bit Manipulation for Coding Interviews

# Introduction

Let's see how we can count the set bits using the **AND** operator.

## What are set-bits?

> 1 = set-bit

> 0 = unset-bit

For example:

```
Input: 5

Output: 0101 (in binary)
```

There are two set bits are two in the above example, as we have two 1's in the binary representation.




# Problem statement
Write a program to count set bits of an integer.

```
Input: 125

Output: 6 
```

**Explanation:** Input has six 1's or set-bits so the output will be 6.

# Basic solution

In this program, a while-loop is iterated until the expression `number > 0` is evaluated to `0` (false).

Let's see the iterations for `number = 125`.

## Iterations  
* After the first iteration,` number(125)` will be divided by `2`, its value will be `62`, and the count incremented to `1`.

* After the second iteration, the value of `number(62)` will be `31` and, the count incremented to `2`.

* After the third iteration, the value of `number(31)` will be `15`, and the count incremented to `3`.

* And so on.

Then the expression is evaluated to false since the `number` is `0`, and the loop terminates.

This is a traditional problem counting the number of set bits or 1's present in a number.

Getting Started

Number Systems, Bitwise, and Binary

Bitwise AND

Bitwise OR

Bitwise NOT

Bitwise XOR

Bit Shifting - Left, Right

Bitwise LeftShift Problems

Bitwise RightShift Problems

Final Thoughts

Challenge 1: Count Set Bits

Introduction

What are set-bits?

Problem statement

Basic solution

Iterations