Remove array elements to reduce frequency of each array element to at most K

// C# program to implement
// the above approach  
using System;
using System.Linq;

class GFG 
{

  // Function to remove array elements 
  // such that frequency of each distinct 
  // array element is at most K 
  static int [] RemoveElemArr(int []arr, 
                              int n, int k) 
  { 

    // Base Case 
    if (n == 0 || n == 1) 
      return arr; 

    // Stores index of array element by removing 
    // the array element such that the frequency 
    // of array elements is at most K 
    int j = 0; 

    // Traverse the array 
    for (int i = 0; i < n; i++) 
    { 

      // If j < k or arr[i] > arr[j - k] 
      if (j < k || arr[i] > arr[j - k]) 
      { 

        // Update arr[j] 
        arr[j++] = arr[i]; 
      } 
    } 

    // Remove array elements 
    while (arr.Length > j)
    { 
      arr = arr.Take(arr.Length - 1).ToArray(); 
    } 

    return arr; 
  } 

  // Function to print the array 
  static void printArray(int [] arr) 
  { 

    // Traverse the array 
    for (int i = 0; i < arr.Length; 
         i++)
    { 
      Console.Write(arr[i] + " "); 
    } 
  } 

  // Utility Function to remove array elements 
  // such that frequency of each distinct 
  // array element is at most K 
  static void UtilRemov(int []arr, int n, int k) 
  { 
    arr = RemoveElemArr(arr, n, k); 

    // Print updated array 
    printArray(arr); 
  } 

  // Driver code
  public static void Main()
  {
    int []arr 
      = { 1, 2, 2, 3, 4, 4, 4, 5, 5 }; 
    int k = 2; 
    int n = arr.Length; 
    UtilRemov(arr, n, k);
  }
}

// This code is contributed by sanjoy_62.

using System;
using System.Collections.Generic;

class Program
{
    // Function to reduce the frequency of elements in the array
    // such that no element appears more than k times
    static List<int> ReduceFrequency(List<int> arr, int k)
    {
        // Create a dictionary to store the frequency of each element
        Dictionary<int, int> freq = new Dictionary<int, int>();
        foreach (int i in arr)
        {
            // Increase the frequency count of element i
            if (freq.ContainsKey(i))
            {
                freq[i]++;
            }
            else
            {
                // If i is not in the dictionary, initialize its frequency to 1
                freq[i] = 1;
            }
        }

        // Create a new list to store the reduced array
        List<int> new_arr = new List<int>();
        foreach (int i in arr)
        {
            // If the frequency of element i is less than or equal to k, include it in the new list
            if (freq[i] <= k)
            {
                new_arr.Add(i);
            }
            // Decrease the frequency count of element i by 2
            freq[i] -= 2;
        }

        return new_arr;
    }

    static void Main(string[] args)
    {
        // Example 1
        List<int> arr1 = new List<int> { 1, 1, 1, 1, 2, 2, 2, 3, 4, 4, 4, 4, 5 };
        int k1 = 3;
        List<int> result1 = ReduceFrequency(arr1, k1);
        Console.Write("Reduced Array 1: ");
        foreach (int i in result1)
        {
            Console.Write(i + " ");
        }
        Console.WriteLine();

        // Example 2
        List<int> arr2 = new List<int> { 1, 2, 2, 3, 4, 4, 4, 5, 5 };
        int k2 = 2;
        List<int> result2 = ReduceFrequency(arr2, k2);
        Console.Write("Reduced Array 2: ");
        foreach (int i in result2)
        {
            Console.Write(i + " ");
        }
        Console.WriteLine();
    }
}