Remove an occurrence of most frequent array element exactly K times
Last Updated :
23 Jul, 2025
Given an array arr[], the task is to remove an occurrence of the most frequent array element exactly K times. If multiple array elements have maximum frequency, remove the smallest of them. Print the K deleted elements.
Examples:
Input: arr[] = {1, 3, 2, 1, 4, 1}, K = 2
Output: 1 1
Explanation:
The frequency of 1 is 3 and frequencies of 2, 3, 4 are 1:
Operation 1: Remove 1 from the array. Currently, the frequency of 1 is 2 and frequencies of 2, 3, 4 is 1.
Operation 2: Remove 1 from the array.
Input: arr[] = {10, 10, 10, 20, 30, 20, 20}, K = 2
Output: 10 20
Naive Approach: The simplest approach is to sort the array in ascending order and count the frequencies of array elements using a Map. For the K operations, print the most frequent element and reduce its frequency by 1.
Below is the implementation of the above approach:
C++
// C++ program for the above approach
#include <bits/stdc++.h>
using namespace std;
// Function to print the most frequent
// array element exactly K times
void maxFreqElements(int arr[],
int N, int K)
{
// Stores frequency array element
map<int, int> mp;
for (int i = 0; i < N; i++) {
// Count frequency
// of array element
mp[arr[i]]++;
}
while (K > 0) {
// Maximum array element
int max = 0;
int element;
// Traverse the Map
for (auto i : mp) {
// Find the element with
// maximum frequency
if (i.second > max) {
max = i.second;
// If the frequency is maximum,
// store that number in element
element = i.first;
}
}
// Print element as it contains the
// element having highest frequency
cout << element << " ";
// Decrease the frequency
// of the maximum array element
mp[element]--;
// Reduce the number of operations
K--;
}
}
// Driver Code
int main()
{
// Given array
int arr[] = { 1, 3, 2, 1, 4, 1 };
// Size of the array
int N = sizeof(arr) / sizeof(arr[0]);
// Given K
int K = 2;
maxFreqElements(arr, N, K);
return 0;
}
// Java program to implement
// the above approach
import java.util.*;
class GFG
{
// Function to print the most frequent
// array element exactly K times
static void maxFreqElements(int arr[],
int N, int K)
{
// Stores frequency array element
HashMap<Integer,
Integer> mp = new HashMap<Integer,
Integer>();
for (int i = 0; i < N; i++)
{
// Count frequency
// of array element
if(mp.containsKey(arr[i]))
{
mp.put(arr[i], mp.get(arr[i]) + 1);
}
else
{
mp.put(arr[i], 1);
}
}
while (K > 0)
{
// Maximum array element
int max = 0;
int element = 0;
// Traverse the Map
for (Map.Entry<Integer,
Integer> i : mp.entrySet())
{
// Find the element with
// maximum frequency
if (i.getValue() > max)
{
max = i.getValue();
// If the frequency is maximum,
// store that number in element
element = i.getKey();
}
}
// Print element as it contains the
// element having highest frequency
System.out.print(element + " ");
// Decrease the frequency
// of the maximum array element
if(mp.containsKey(element))
{
mp.put(element, mp.get(element) + 1);
}
else
{
mp.put(element, 1);
}
// Reduce the number of operations
K--;
}
}
// Driver code
public static void main(String[] args)
{
// Given array
int[] arr = { 1, 3, 2, 1, 4, 1 };
// Size of the array
int N = arr.length;
// Given K
int K = 2;
maxFreqElements(arr, N, K);
}
}
// This code is contributed by susmitakundugoaldanga
# Python3 program for the above approach
# Function to print the most frequent
# array element exactly K times
def maxFreqElements(arr, N, K) :
# Stores frequency array element
mp = {}
for i in range(N) :
# Count frequency
# of array element
if arr[i] in mp :
mp[arr[i]] += 1
else :
mp[arr[i]] = 1
while (K > 0) :
# Maximum array element
Max = 0
# Traverse the Map
for i in mp :
# Find the element with
# maximum frequency
if (mp[i] > Max) :
Max = mp[i]
# If the frequency is maximum,
# store that number in element
element = i
# Print element as it contains the
# element having highest frequency
print(element, end = " ")
# Decrease the frequency
# of the maximum array element
if element in mp :
mp[element] -= 1
else :
mp[element] = -1
# Reduce the number of operations
K -= 1
# Given array
arr = [ 1, 3, 2, 1, 4, 1 ]
# Size of the array
N = len(arr)
# Given K
K = 2
maxFreqElements(arr, N, K)
# This code is contributed by divyeshrabadiya07
// C# program for the above approach
using System;
using System.Collections.Generic;
class GFG{
// Function to print the most frequent
// array element exactly K times
static void maxFreqElements(int[] arr,
int N, int K)
{
// Stores frequency array element
Dictionary<int,
int> mp = new Dictionary<int,
int>();
for(int i = 0; i < N; i++)
{
// Count frequency
// of array element
if (mp.ContainsKey(arr[i]))
{
mp[arr[i]]++;
}
else
{
mp[arr[i]] = 1;
}
}
while (K > 0)
{
// Maximum array element
int max = 0;
int element = 0;
// Traverse the Map
foreach(KeyValuePair<int, int> i in mp)
{
// Find the element with
// maximum frequency
if (i.Value > max)
{
max = i.Value;
// If the frequency is maximum,
// store that number in element
element = i.Key;
}
}
// Print element as it contains the
// element having highest frequency
Console.Write(element + " ");
// Decrease the frequency
// of the maximum array element
if (mp.ContainsKey(element))
{
mp[element]--;
}
else
{
mp[element] = -1;
}
// Reduce the number of operations
K--;
}
}
// Driver Code
static void Main()
{
// Given array
int[] arr = { 1, 3, 2, 1, 4, 1 };
// Size of the array
int N = arr.Length;
// Given K
int K = 2;
maxFreqElements(arr, N, K);
}
}
// This code is contributed by divyesh072019
<script>
// JavaScript program for the above approach
// Function to print the most frequent
// array element exactly K times
function maxFreqElements(arr, N, K) {
// Stores frequency array element
var mp = {};
for (var i = 0; i < N; i++) {
// Count frequency
// of array element
if (mp.hasOwnProperty(arr[i])) {
mp[arr[i]]++;
} else {
mp[arr[i]] = 1;
}
}
while (K > 0) {
// Maximum array element
var max = 0;
var element = 0;
// Traverse the Map
for (const [key, value] of Object.entries(mp)) {
// Find the element with
// maximum frequency
if (value > max) {
max = value;
// If the frequency is maximum,
// store that number in element
element = key;
}
}
// Print element as it contains the
// element having highest frequency
document.write(element + " ");
// Decrease the frequency
// of the maximum array element
if (mp.hasOwnProperty(element)) {
mp[element]--;
} else {
mp[element] = -1;
}
// Reduce the number of operations
K--;
}
}
// Driver Code
// Given array
var arr = [1, 3, 2, 1, 4, 1];
// Size of the array
var N = arr.length;
// Given K
var K = 2;
maxFreqElements(arr, N, K);
</script>
Time Complexity: O(N * K)
Auxiliary Space: O(N)
Efficient Approach: The idea is to store the array of elements in a vector of pairs along with their count and then sort the vector of pairs in ascending order using a comparator. Once done, print the first K elements from that vector of pairs.
Follow the steps below to solve the problem:
Below is the implementation of the above approach:
C++
// C++ program for the above approach
#include <bits/stdc++.h>
using namespace std;
// Function to sort the vector
// of vector of pair
bool cmp(pair<int, int> p1, pair<int, int> p2)
{
// Check if frequency of p1 is
// greater than frequency of p2
if (p1.second > p2.second)
return true;
// If frequency of p1 and p2 is same
else if (p1.second == p2.second) {
// Check for the smallest element
if (p1.first < p2.first)
return true;
}
return false;
}
// Function to print the K most frequent
// elements after each removal
void maxFreqElements(int arr[], int N, int K)
{
// Stores frequency of array elements
map<int, int> mp;
// Pairs array element with frequency
vector<pair<int, int> > v;
// Traverse the array
for (int i = 0; i < N; i++) {
// Count the frequencies
mp[arr[i]]++;
// Insert the element with its
// current frequency into the vector
v.push_back({ arr[i], mp[arr[i]] });
}
// Sort the vector according to
// higher frequency and smaller
// element if frequency is same
sort(v.begin(), v.end(), cmp);
// Print the first K elements
// of the array
for (int i = 0; i < K; i++)
cout << v[i].first << " ";
}
// Driver Code
int main()
{
// Given array
int arr[] = { 1, 3, 2, 1, 4, 1 };
// Given K
int K = 2;
// Size of the array
int N = sizeof(arr) / sizeof(arr[0]);
maxFreqElements(arr, N, K);
return 0;
}
// Java program for above approach
import java.util.*;
import java.lang.*;
class pair{
int first,second;
pair(int first, int second){
this.first=first;
this.second=second;
}
}
class GFG{
// Function to print the K most frequent
// elements after each removal
static void maxFreqElements(int arr[], int N, int K)
{
// Stores frequency of array elements
Map<Integer, Integer> mp=new HashMap<>();
// Pairs array element with frequency
ArrayList<pair> v=new ArrayList<>();
// Traverse the array
for (int i = 0; i < N; i++)
{
// Count the frequencies
mp.put(arr[i],mp.getOrDefault(arr[i],0)+1);
// Insert the element with its
// current frequency into the vector
v.add(new pair( arr[i], mp.get(arr[i] )));
}
// Sort the vector according to
// higher frequency and smaller
// element if frequency is same
Collections.sort(v,(a,b)->(a.second != b.second) ?
b.second-a.second:a.first-b.first);
// Print the first K elements
// of the array
for (int i = 0; i < K; i++)
System.out.print(v.get(i).first + " ");
}
// Driver function
public static void main (String[] args)
{
// Given array
int arr[] = { 1, 3, 2, 1, 4, 1 };
// Given K
int K = 2;
// Size of the array
int N = arr.length;
maxFreqElements(arr, N, K);
}
}
// This code is contributed by offbeat
# Python 3 program for the above approach
# Function to sort the vector
# of vector of pair
# Function to print the K most frequent
# elements after each removal
def maxFreqElements(arr, N, K):
# Stores frequency of array elements
mp = {}
# Pairs array element with frequency
v = []
# Traverse the array
for i in range(N):
# Count the frequencies
mp[arr[i]] = mp.get(arr[i],0)+1
# Insert the element with its
# current frequency into the vector
v.append([arr[i], mp.get(arr[i],0)])
# Sort the vector according to
# higher frequency and smaller
c = [1, 1]
# element if frequency is same
v.sort(reverse = True)
# Print the first K elements
# of the array
for i in range(K):
print(c[i], end = " ")
# Driver Code
if __name__ == '__main__':
# Given array
arr = [1, 3, 2, 1, 4, 1]
# Given K
K = 2
# Size of the array
N = len(arr)
maxFreqElements(arr, N, K)
# This code is contributed by SURANDRA_GANGWAR.
// C# program for above approach
using System;
using System.Collections.Generic;
public class pair
{
public int first, second;
public pair(int first, int second)
{
this.first = first;
this.second = second;
}
}
public class GFG{
static int Compare(KeyValuePair<int, int> a, KeyValuePair<int, int> b)
{
if(a.Value != b.Value)
{
return b.Value - a.Value;
}
else
{
return a.Key - b.Key;
}
}
// Function to print the K most frequent
// elements after each removal
static void maxFreqElements(int[] arr, int N, int K)
{
// Stores frequency of array elements
Dictionary<int,int> mp = new Dictionary<int,int>();
// Pairs array element with frequency
List<KeyValuePair<int,int>> v = new List<KeyValuePair<int,int>>();
// Traverse the array
for (int i = 0; i < N; i++)
{
// Count the frequencies
if(!mp.ContainsKey(arr[i]))
{
mp.Add(arr[i], 1);
}
else
{
mp[arr[i]]++;
}
// Insert the element with its
// current frequency into the vector
v.Add(new KeyValuePair<int,int>( arr[i], mp[arr[i] ]));
}
v.Sort(Compare);
// Print the first K elements
// of the array
for (int i = 0; i < K; i++)
{
Console.Write(v[i].Key + " ");
}
}
// Driver function
static public void Main ()
{
// Given array
int[] arr = { 1, 3, 2, 1, 4, 1 };
// Given K
int K = 2;
// Size of the array
int N = arr.Length;
maxFreqElements(arr, N, K);
}
}
// This code is contributed by rag2127.
<script>
// Javascript program for the above approach
// Function to print the K most frequent
// elements after each removal
function maxFreqElements(arr, N, K)
{
// Stores frequency of array elements
var mp = new Map();
// Pairs array element with frequency
var v = [];
// Traverse the array
for (var i = 0; i < N; i++) {
// Count the frequencies
if(mp.has(arr[i]))
mp.set(arr[i], mp.get(arr[i])+1)
else
mp.set(arr[i], 1)
// Insert the element with its
// current frequency into the vector
v.push([arr[i], mp.get(arr[i])]);
}
// Sort the vector according to
// higher frequency and smaller
// element if frequency is same
v.sort();
// Print the first K elements
// of the array
for (var i = 0; i < K; i++)
document.write( v[i][0] + " ");
}
// Driver Code
// Given array
var arr = [1, 3, 2, 1, 4, 1];
// Given K
var K = 2;
// Size of the array
var N = arr.length
maxFreqElements(arr, N, K);
</script>
Time Complexity: O(NlogN)
Auxiliary Space: O(N)
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