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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Python3

# 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 [tabbyending] Output:

1 3 3 4

Time Complexity – O(N)



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Improved By : sahilshelangia