Welcome to our detailed guide on bit manipulation problems! If you’re preparing for coding interviews or just want to strengthen your understanding of bitwise operations, you’re in the right place. In this article, we’ll dive deep into two classic problems: swapping two numbers without using a temporary variable and checking if the Kth bit is set in a number’s binary representation. We’ll explain everything in simple, plain English to make it easy for students to follow along.<\/p>\n\n\n\n
These problems are common in platforms like GeeksforGeeks and LeetCode, and they help build a strong foundation in data structures and algorithms. We’ll cover problem statements, intuitions, approaches, code examples, dry runs, edge cases, and time\/space complexities. By the end, you’ll feel confident tackling similar challenges.<\/p>\n\n\n\n
Let’s start with the first problem.<\/p>\n\n\n
Swapping two numbers is a basic operation, but doing it without extra space (like a temporary variable) is a neat trick using bitwise XOR. This method is efficient and works in constant time, making it perfect for constrained environments.<\/p>\n\n\n\n
Objective:<\/strong> Swap the values of two integers, a and b, without using any temporary variable.<\/p>\n\n\n\n Expected Input and Output:<\/strong><\/p>\n\n\n\n Examples:<\/strong><\/p>\n\n\n\n Constraints:<\/strong><\/p>\n\n\n\n Expected Time Complexity:<\/strong> O(1) This problem is straightforward but teaches us about bitwise operations’ power. You don’t need to handle input\/output; just complete the function that returns the swapped list.<\/p>\n\n\n\n Intuition:<\/strong> We use the XOR (^) operator, a bitwise operation that flips bits. XOR has useful properties:<\/p>\n\n\n\n These properties allow us to swap without losing data. Imagine XOR as a way to “encode” and “decode” values temporarily.<\/p>\n\n\n\n Approach:<\/strong><\/p>\n\n\n\n This works because each step builds on the previous one, using XOR to toggle between values.<\/p>\n\n\n\n Here’s the simple Python code for the solution:<\/p>\n\n\n\n\n
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Expected Auxiliary Space:<\/strong> O(1)<\/p>\n\n\n\nIntuition and Approach<\/h3>\n\n\n\n
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Code Example in Python<\/h3>\n\n\n\n