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Grokking Bit Manipulation for Coding Interviews

Detect If Two Integers Have Opposite Signs

Understand how to detect if two integers have opposite signs by using the bitwise XOR operator. This lesson explains the concept of sign detection through the most significant bit and demonstrates a constant time solution without extra memory. Master this technique to optimize bit manipulation problems in coding interviews.

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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 ...