Frequency Of Elements

Sep 15, 2022 · 1 min read

Question

Q. Program to find the frequency of each element of an array.

Algorithm

Step 1: Create a map of integer to store key-value pairs. map<int,int>.
Step 2: Now iterate over all the elements of the array and count their frequency by the help of map.
Step 3: Now make a iterator for map to iterate over the map items.
Step 4: This is the final step. Just print all the elements and their frequency stored in map respectively.

Code

Here is the C++ implementation of the given problem

#include<iostream>
#include<map>
#include<vector>
using namespace std;
int main()
{
    map<int,int> m;
    int n; //Number of elements in array
    cin>>n;
    vector<int> arr(n);
    for(int i = 0; i < n; i++){
        cin>>arr[i];
    }
    for(int x: arr){
        m[x]++; //main line for solving this problem
    }
    map<int, int> :: iterator it;
    for(it = m.begin(); it != m.end(); it++){
        cout<<it->first<<"->"<<it->second<<endl;
    }
    return 0;
}

Output
10
1 5 2 1 5 3 2 2 5 2
1->2
2->4
3->1
5->3