# Find the frequencies of all duplicates elements in the array

• Difficulty Level : Easy
• Last Updated : 01 Jul, 2021

Given an array of integers with duplicate elements in it, the task is to find the duplicate elements in the array and their frequencies.
Examples:

Input: arr[] = {2, 3, 4, 5, 4, 6, 4, 7, 4, 5, 6, 6}
Output: Below is the frequency of repeated elements –
4 –> 4
5 –> 2
6 –> 3
Input: arr[] = {4, 4, 5, 5, 6}
Output: Below is the frequency of repeated elements –
4 –> 2
5 –> 2

Approach:

• Create a Hash Map to store the frequency of the elements.
• Elements whose frequency is greater than 1 are the repeated elements.

Below is the implementation of the above approach:

## CPP

 `// CPP Implementation to find the``// repeating elements with there count``#include``using` `namespace` `std;` `// Function to find the repeating``// elements with there count``map<``int``,``int``> findRepeating(``int` `arr[], ``int` `size){` `    ``// Hash map to store the``    ``// frequency of elements``    ``map<``int``,``int``> frequency;``    ` `    ``// Loop to store the frequency of``    ``// elements of array``    ``for` `(``int` `i = 0; i < size; i++)``    ``frequency[arr[i]]++;``    ``return` `frequency;``}``        ` `// Driver Code``int` `main(){``    ``int` `arr[] = {4, 4, 5, 5, 6};``    ``int` `arr_size = ``sizeof``(arr)/``sizeof``(arr);``    ``map<``int``,``int``> frequency = findRepeating(arr, arr_size);``    ``cout<<``"Below is the frequency of repeated elements -"``< 1)``            ``cout< "``<

## Java

 `// Java Implementation to find the``// repeating elements with there count``import` `java.util.*;` `class` `GFG``{``    ` `// Function to find the repeating``// elements with there count``static` `HashMap findRepeating(``int` `[]arr, ``int` `size){``    ` `    ``// Hash map to store the``    ``// frequency of elements``    ``HashMap frequency = ``new` `HashMap();``    ` `    ``// Loop to store the frequency of``    ``// elements of array``    ``for``(``int` `i = ``0``; i < size; i++)``    ``{``        ``if``(frequency.containsKey(arr[i]))``        ``{``            ``frequency.put(arr[i], frequency.get(arr[i]) + ``1``);``        ``}``        ``else``        ``{``            ``frequency.put(arr[i], ``1``);``        ``}``    ``}``    ``return` `frequency;``}` `// Driver Code``public` `static` `void` `main(String []args)``{``    ``int` `[]arr = {``4``, ``4``, ``5``, ``5``, ``6``};``    ``int` `arr_size = arr.length;``    ``HashMap frequency = findRepeating(arr, arr_size);``    ``System.out.println(``"Below is the frequency"``    ``+``"of repeated elements -"``);``    ``for` `(Map.Entry entry : frequency.entrySet())``        ``if` `(entry.getValue() > ``1``)``            ``System.out.println(entry.getKey()+ ``" --> "``+entry.getValue());``}``}` `// This code is contributed by PrinciRaj1992`

## Python

 `# Python Implementation to find the``# repeating elements with there count` `# Function to find the repeating``# elements with there count``def` `findRepeating(arr, size):``    ` `    ``# Hash map to store the``    ``# frequency of elements``    ``frequency ``=` `{}``    ` `    ``# Loop to store the frequency of``    ``# elements of array``    ``for` `i ``in` `range` `(``0``, size):``        ``frequency[arr[i]] ``=` `\``        ``frequency.get(arr[i], ``0``) ``+` `1``    ``return` `frequency``    ` `# Driver Code``if` `__name__ ``=``=` `"__main__"``:``    ``arr ``=` `[``4``, ``4``, ``5``, ``5``, ``6``]``    ``arr_size ``=` `len``(arr)``    ``frequency ``=` `findRepeating(arr, arr_size)``    ``print``("Below ``is` `the frequency\``    ``of repeated elements ``-``")``    ``for` `i ``in` `frequency:``        ``if` `frequency[i] > ``1``:``            ``print``(i, ``" --> "``, frequency[i])`

## C#

 `// C# Implementation to find the``// repeating elements with there count``using` `System;``using` `System.Collections.Generic;` `class` `GFG``{``    ` `// Function to find the repeating``// elements with there count``static` `Dictionary<``int``, ``int``> findRepeating(``int` `[]arr, ``int` `size){``    ` `    ``// Hash map to store the``    ``// frequency of elements``    ``Dictionary<``int``,``int``> frequency = ``new` `Dictionary<``int``,``int``>();``    ` `    ``// Loop to store the frequency of``    ``// elements of array``    ``for``(``int` `i = 0; i < size; i++)``    ``{``        ``if``(frequency.ContainsKey(arr[i]))``        ``{``            ``frequency[arr[i]] = frequency[arr[i]] + 1;``        ``}``        ``else``        ``{``            ``frequency.Add(arr[i], 1);``        ``}``    ``}``    ``return` `frequency;``}` `// Driver Code``public` `static` `void` `Main(String []args)``{``    ``int` `[]arr = {4, 4, 5, 5, 6};``    ``int` `arr_size = arr.Length;``    ``Dictionary<``int``,``int``> frequency = findRepeating(arr, arr_size);``    ``Console.WriteLine(``"Below is the frequency"``                        ``+``"of repeated elements -"``);``    ``foreach` `(KeyValuePair<``int``,``int``> entry ``in` `frequency)``        ``if` `(entry.Value > 1)``            ``Console.WriteLine(entry.Key+ ``" --> "``+entry.Value);``}``}` `// This code is contributed by 29AjayKumar`

## Javascript

 ``

Output:

```Below is the frequency    of repeated elements -
4  -->  2
5  -->  2```

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