Code : 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 second array/list (ARR2).

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<bits/stdc++.h>

void printIntersection(int arr1[], int arr2[], int n, int m) {

// Write your code here

unordered_map<int,int>mp;

for(int i=0;i<n;i++)

mp[arr1[i]]++;

for(int i=0;i<m;i++){

if(mp.count(arr2[i])>0){

cout<<arr2[i]<<endl;

mp[arr2[i]]--;

if(mp[arr2[i]]==0) mp.erase(arr2[i]);

}

}

// for(int i=0;i<m;i++){

// if(mp.count(arr2[i])>0){// present hai ke nahi

// cout<<arr2[i]<<endl;

// mp[arr2[i]]--;

// if(mp[arr2[i]]==0) mp.erase(arr2[i]);

// }

// }

}