Remove elements from the array which appear more than k times

Given an array of integers, remove all the occurrences of those elements which appear strictly more than k times in the array.

Examples:

Input : arr[] = {1, 2, 2, 3, 2, 3, 4}
        k = 2
Output : 1 3 3 4

Input : arr[] = {2, 5, 5, 7}
        k = 1
Output : 2 7

Approach:

  • Take a hash map, which will store the frequency of all the elements in the array.
  • Now, traverse once again.
  • Print the elements which appear less than or equal to k times.

C++

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// C++ program to remove the elements which
// appear more than k times from the array.
#include "iostream"
#include "unordered_map"
using namespace std;
  
void RemoveElements(int arr[], int n, int k)
{
    // Hash map which will store the
    // frequency of the elements of the array.
    unordered_map<int, int> mp;
  
    for (int i = 0; i < n; ++i) {
        // Incrementing the frequency
        // of the element by 1.
        mp[arr[i]]++;
    }
  
    for (int i = 0; i < n; ++i) {
        // Print the element which appear
        // less than or equal to k times.
        if (mp[arr[i]] <= k) {
            cout << arr[i] << " ";
        }
    }
}
  
int main(int argc, char const* argv[])
{
    int arr[] = { 1, 2, 2, 3, 2, 3, 4 };
    int n = sizeof(arr) / sizeof(arr[0]);
  
    int k = 2;
  
    RemoveElements(arr, n, k);
    return 0;
}

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Java














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// Java program to remove the elements which 


// appear more than k times from the array. 


import java.util.HashMap; 


import java.util.Map; 


  


class GFG  


{  


  


static void RemoveElements(int arr[], int n, int k) 


{ 


    // Hash map which will store the 


    // frequency of the elements of the array. 


    Map<Integer,Integer> mp = new HashMap<>(); 


  


    for (int i = 0; i < n; ++i) 


    { 


        // Incrementing the frequency 


        // of the element by 1. 


        mp.put(arr[i],mp.get(arr[i]) == null?1:mp.get(arr[i])+1); 


  


    } 


  


    for (int i = 0; i < n; ++i)  


    { 


        // Print the element which appear 


        // less than or equal to k times. 


        if (mp.containsKey(arr[i]) && mp.get(arr[i]) <= k) 


        { 


            System.out.print(arr[i] + " "); 


        } 


    } 


} 


  


// Driver code  


public static void main(String[] args)  


{ 


    int arr[] = { 1, 2, 2, 3, 2, 3, 4 }; 


    int n = arr.length; 


  


    int k = 2; 


  


    RemoveElements(arr, n, k); 


      


} 


} 


  


// This code is contributed by Rajput-Ji 



















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Python3














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# Python 3 program to remove the elements which 


# appear more than k times from the array. 


def RemoveElements(arr, n, k): 


      


    # Hash map which will store the 


    # frequency of the elements of the array. 


    mp = {i:0 for i in range(len(arr))} 


  


    for i in range(n): 


          


        # Incrementing the frequency 


        # of the element by 1. 


        mp[arr[i]] += 1


  


    for i in range(n): 


          


        # Print the element which appear 


        # less than or equal to k times. 


        if (mp[arr[i]] <= k): 


            print(arr[i], end = " ") 


  


# Driver Code     


if __name__ == '__main__': 


    arr = [1, 2, 2, 3, 2, 3, 4] 


    n = len(arr) 


  


    k = 2


  


    RemoveElements(arr, n, k) 


  


# This code is contributed by 


# Sahil_Shelangia 



















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Output:


1 3 3 4



Time Complexity – O(N)



          
          
          
          

            

    

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Improved By :  sahilshelangia, Rajput-Ji