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Day 8 - Challenge 1 - Intersection of Two Arrays

Finding the Intersection of Two Arrays using JavaScript

Introduction 

Arrays are an essential data structure in programming, allowing us to store and manipulate collections of elements. In many scenarios, we need to find common elements between two arrays. This process is commonly referred to as finding the "intersection" of two arrays. In this blog post, we'll explore a simple and efficient JavaScript program to find the intersection of two arrays.

The Problem 

Given two arrays, our task is to find the distinct common elements between them. In other words, we want to identify the values that appear in both arrays without any duplicates.

Approach 

We'll use a hash set to keep track of elements from one array and then iterate through the second array to identify common elements.

Here's a step-by-step breakdown of our approach:

  1. Create an empty hash set.
  2. Iterate through the first array and add each element to the hash set.
  3. Create an empty result array to store the intersection.
  4. Iterate through the second array. If the element exists in the hash set, add it to the result array and remove it from the hash set to avoid duplicate intersections.
  5. Return the result array containing the distinct common elements.

JavaScript Program

function findIntersection(nums1, nums2) {
    const set = new Set();
    const intersection = [];
    // Add elements from the first array to the hash set
    for (const num of nums1) {
        set.add(num);
    }
    // Iterate through the second array
    for (const num of nums2) {
        if (set.has(num)) {
            intersection.push(num);
            set.delete(num); // Avoid duplicates
        }
    }
    return intersection;
}

// Example usage
const array1 = [1, 2, 2, 1];
const array2 = [2, 2];
const result = findIntersection(array1, array2);
console.log(result); // Output: [2]

Demo

Array Intersection Demo

Intersection Result:


Conclusion 

Finding the intersection of two arrays is a common task in programming, and a hash set provides an efficient way to achieve this. By using a hash set to store elements from one array and then checking for their presence in the second array, we can identify common elements while avoiding duplicates. The JavaScript program provided in this blog post demonstrates a straightforward solution to the problem.

This approach has a time complexity of O(n), where n is the total number of elements in both arrays, and a space complexity of O(min(m, n)), where m and n are the lengths of the two arrays, respectively. This efficient approach makes it suitable for handling arrays of varying sizes.

Now write the same program in your favorite language in comment section. 

Other Challenges:

  1. Day 5 Challenges
  2. Day 6 Challenges 
  3. Day 7 Challenges

 

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