Print intersection.cpp

/*
Print Intersection
You have been given two integer arrays/lists (ARR1 and ARR2) of size N and M, respectively. You need to print their intersection; 
An intersection for this problem can be defined when both the arrays/lists contain a particular value or to put it in other words, 
when there is a common value that exists in both the arrays/lists.

Note : Input arrays/lists can contain duplicate elements.

The intersection elements printed would be in the order they appear in the first sorted array/list (ARR1).


Input format :
The first line of input contains an integer 'N' representing the size of the first array/list.

The second line contains 'N' single space separated integers representing the elements of the first the array/list.

The third line contains an integer 'M' representing the size of the second array/list.

The fourth line contains 'M' single space separated integers representing the elements of the second array/list.
Output format :
Print the intersection elements. Each element is printed in a separate line.

Constraints :
0 <= N <= 10^6
0 <= M <= 10^6

Time Limit: 1 sec 

Sample Input 1 :
6
2 6 8 5 4 3
4
2 3 4 7 

Sample Output 1 :
2
3 
4


Sample Input 2 :
4
2 6 1 2
5
1 2 3 4 2

Sample Output 2 :
1 
2 
2
*/

#include<unordered_map>
#include<utility>
void printIntersection(int arr1[], int arr2[], int n, int m) {
    // Write your code here
    unordered_map<int, int> map;
    
    for(int i = 0; i < n; i++) {
        map[arr1[i]]++;
    }
    
    for(int i = 0; i < m; i++) {
      	if(map[arr2[i]]) {
            cout << arr2[i] << endl;
            map[arr2[i]]--;
        } else {
            continue;
        }
    }  
}

// Time Complexity : O(n)
// Auxillary Space : O(n)