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

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

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++

 // 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 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);        int k = 2;        RemoveElements(arr, n, k);     return 0; }

Java

 // 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 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

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

Output:

1 3 3 4

Time Complexity – O(N)

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Improved By : sahilshelangia, Rajput-Ji

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