Intersection of Two Arrays II

Given two integer arrays ARR1 and ARR2 of size N and M respectively, find the intersection of these arrays. An intersection refers to elements that appear in both arrays.

Note:

Input arrays/lists can contain duplicate elements. The intersection elements returned should be in the order they appear in the first array/list (ARR1).

Example:

Input:

t = 1
N = 3
ARR1 = [1, 2, 2]
M = 2
ARR2 = [2, 3]

Output:

2

Explanation:

The element '2' is common in both arrays and appears in the first array.

Constraints:

1 ≤ t ≤ 10²

0 ≤ N ≤ 10⁵

0 ≤ M ≤ 10⁵

Time Limit: 1 second.

Question

Intersection of Two Arrays II

Given two integer arrays ARR1 and ARR2 of size N and M respectively, find the intersection of these arrays. An intersection refers to elements that appear in both arrays.

Note:

Input arrays/lists can contain duplicate elements. The intersection elements returned should be in the order they appear in the first array/list (ARR1).

Example:

Input:

t = 1 
N = 3 
ARR1 = [1, 2, 2] 
M = 2 
ARR2 = [2, 3]

Output:

Explanation:

The element '2' is common in both arrays and appears in the first array.

Constraints:

1 ≤ t ≤ 10²
0 ≤ N ≤ 10⁵
0 ≤ M ≤ 10⁵
Time Limit: 1 second.

Accepted Answer

Find the intersection of two integer arrays in the order they appear in the first array.

Iterate through the first array and store elements in a hashmap with their frequencies.
Iterate through the second array and check if the element exists in the hashmap, decrement frequency if found.
Return the elements that have non-zero frequencies as the intersection.