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

In this question, input two numbers and detect if they have opposite signs.

# Problem statement
We need to write a program to detect if two input integers have opposite signs.

```
Input: a = 100, b = -1
 
Output: "Signs are opposite"
```

```
Input: a = 100, b = 501
 
Output: "Signs are not opposite."
```

## Concept

We have already learned about representing/finding a positive/negative number in the `NOT` lesson.

Two rules:
> If the leading bit on the left side is 0, then it is a positive number.

> If the leading bit on the left side is 1, then it is a negative number.

# Solution

The XOR rule says the output will be `1` only when two input values are opposite (0 and 1, or 1 and 0). 

The above concept clearly says if the leading left-MSB (left-most significant bit) is `1`, then it's negative. 

The following four examples will clearly explain these concepts.

- Consider two numbers whose left MSBs are both `1`, and the XOR of them is `0`.

- If two numbers both have left MSBs of `0`, then the XOR of them is `0`.

- Now, when the left MSB of two inputs is different, then the XOR yields to `1`, which is a negative number.

So, when we perform `(x ^ y) < 0`, we get the right answer.

In this lesson, we detect if two integers have different signs. Ignore the values of the inputs for this problem and focus on the signs. 

Detect If Two Integers Have Opposite Signs

In this lesson, we detect if two integers have different signs. Ignore the values of the inputs for this problem and focus on the signs.

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

Detect If Two Integers Have Opposite Signs

Introduction

Problem statement

Concept