How to use the map In Javascript

Union:

Creating functions and passing both arrays and their respective lengths.
Initializing a map mp and storing the element’s key value pairwise.
Iterating mp and storing unique value using mp.keys() function into an array.
Printing array in the console.

Intersection:

Creating functions and passing both arrays and their respective lengths.
Initializing a map mp and storing the elements of the first array in key-value pairwise
Iterating the second array and checking for the presence of each element in the mp map, If that element is present in mp then we will add that element into the intersection array.
And will delete that element from mp for the avoidance of duplicates in the intersection array.

Example: This example describes the union & intersection of 2 unsorted Arrays by implementing the Map.

Javascript

function printUnion(a, n, b, m) { 
    let mp = new Map(); 
  
    // Inserting array elements in mp 
    for (let i = 0; i < n; i++) { 
        mp.set(a[i], i); 
    } 
    for (let i = 0; i < m; i++) { 
        mp.set(b[i], i); 
    } 
  
    let ans = []; 
    for (let key of mp.keys()) { 
        ans.push(key) 
    } 
    console.log(ans); 
} 
function getIntersection(a, n, b, m) { 
    let mp = new Map(); 
    let ans = []; 
  
    // Inserting elements from array 'a' into the Map 
    for (let i = 0; i < n; i++) { 
        mp.set(a[i], i); 
    } 
  
    console.log("Intersection:"); 
    for (let i = 0; i < m; i++) { 
        if (mp.has(b[i])) { 
            ans.push(b[i]); 
              
            // Map to avoid duplicates in the intersection 
            mp.delete(b[i]); 
        } 
    } 
    console.log(ans); 
} 
  
// Driver Code 
  
let a = [1, 2, 5, 6, 2, 3, 5, 7, 3]; 
let b = [2, 4, 5, 6, 8, 9, 4, 6, 5, 4]; 
printUnion(a, a.length, b, b.length); 
getIntersection(a, a.length, b, b.length);

Output

[
  1, 2, 5, 6,
  3, 4, 8, 9
]
Intersection:
[ 2, 5, 6 ]

Time Complexity: O(m * log(m) + n * log(n))

Auxiliary Space: O(m + n)

JavaScript Program to Find Union and Intersection of Two Unsorted Arrays

In this article, we will learn how to find the Union and Intersection of two arrays. When an array contains all the elements that are present in both of the arrays, it is called a union. On the other hand, if an array has only those elements that are common in both of the arrays, then it is called an intersection.

Example

Input: 
a = [1,3,5,7,9]  , b = [1,2,3,4,6,8,10]

Output: 
Union: [1,2,3,4,5,6,7,8,9,10]
Intersection: ans =[1,3]

Table of Content

Using Set
Using the map
Use Sorting
Use Sorting and Searching
Without using hashing or any predefined library like sets or maps and works even for both repeated and distant elements
Kind of hashing technique without using any predefined JavaScript Collections

We will understand the various approaches for finding the union and the intersection of two unsorted Arrays.

Tags:

#javascript-array #JavaScript-DSA #JavaScript-Program #JavaScript #Web Technologies

Using Set

Use Sorting

How to use the map In Javascript

Union:

Intersection:

Javascript

JavaScript Program to Find Union and Intersection of Two Unsorted Arrays

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