Given an array arr containing integers of size N, the task is to delete all the elements from the array that have odd frequencies.
Examples:
Input: arr[] = {3, 3, 3, 2, 2, 4, 7, 7}
Output: {2, 2, 7, 7}
Explanation:
Frequency of 3 = 3
Frequency of 2 = 2
Frequency of 4 = 1
Frequency of 7 = 2
Therefore, the elements 3 and 4 have odd frequencies, and hence they are removed.
Input: arr[] = {1, 3, 3, 1, 2, 5, 6, 5}
Output: {1, 3, 3, 1, 5, 5}
Approach:
- Create a map and store the frequency of each element from the array to the same map.
- Then, traverse the array and find out which elements have odd frequencies with the help of the map.
- Ignore all those elements which have odd frequencies and print rest of them
Below is the implementation of the above approach:
C++
// C++ program to removes all odd// frequency elements from an Array#include <bits/stdc++.h>using namespace std;// Function that removes the// elements which have odd// frequencies in the arrayvoid remove(int arr[], int n){ // Create a map to store the // frequency of each element unordered_map<int, int> m; for (int i = 0; i < n; i++) { m[arr[i]]++; } // Remove the elements which // have odd frequencies for (int i = 0; i < n; i++) { // If the element has // odd frequency then skip if ((m[arr[i]] & 1)) continue; cout << arr[i] << ", "; }}// Driver codeint main(){ int arr[] = { 3, 3, 3, 2, 2, 4, 7, 7 }; int n = sizeof(arr) / sizeof(arr[0]); // Function call remove(arr, n); return 0;} |
Java
// Java program to removes all odd// frequency elements from an Arrayimport java.util.*;class GFG { // Function that removes the // elements which have odd // frequencies in the array static void remove(int arr[], int n) { // Create a map to store the // frequency of each element HashMap<Integer, Integer> mp = new HashMap<Integer, Integer>(); for (int i = 0; i < n; i++) { if (mp.containsKey(arr[i])) { mp.put(arr[i], mp.get(arr[i]) + 1); } else { mp.put(arr[i], 1); } } // Remove the elements which // have odd frequencies for (int i = 0; i < n; i++) { // If the element has // odd frequency then skip if ((mp.containsKey(arr[i]) && mp.get(arr[i]) % 2 == 1)) continue; System.out.print(arr[i] + ", "); } } // Driver code public static void main(String[] args) { int arr[] = { 3, 3, 3, 2, 2, 4, 7, 7 }; int n = arr.length; // Function call remove(arr, n); }}// This code is contributed by Rajput-Ji |
Python3
# Python3 program to removes all odd # frequency elements from an Array # Function that removes the # elements which have odd # frequencies in the array def remove(arr, n) : # Create a map to store the # frequency of each element m = dict.fromkeys(arr,0); for i in range(n) : m[arr[i]] += 1; # Remove the elements which # have odd frequencies for i in range(n) : # If the element has # odd frequency then skip if ((m[arr[i]] & 1)) : continue; print(arr[i],end= ", "); # Driver code if __name__ == "__main__" : arr = [ 3, 3, 3, 2, 2, 4, 7, 7 ]; n = len(arr); # Function call remove(arr, n); # This code is contributed by Yash_R |
C#
// C# program to removes all odd// frequency elements from an Arrayusing System;using System.Collections.Generic;class GFG { // Function that removes the // elements which have odd // frequencies in the array static void remove(int []arr, int n) { // Create a map to store the // frequency of each element Dictionary<int, int> mp = new Dictionary<int, int>(); for (int i = 0; i < n; i++) { if (mp.ContainsKey(arr[i])) { mp[arr[i]] = mp[arr[i]] + 1; } else { mp.Add(arr[i], 1); } } // Remove the elements which // have odd frequencies for (int i = 0; i < n; i++) { // If the element has // odd frequency then skip if ((mp.ContainsKey(arr[i]) && mp[arr[i]] % 2 == 1)) continue; Console.Write(arr[i] + ", "); } } // Driver code public static void Main(String[] args) { int []arr = { 3, 3, 3, 2, 2, 4, 7, 7 }; int n = arr.Length; // Function call remove(arr, n); }}// This code is contributed by 29AjayKumar |
Javascript
<script>// Javascript program to removes all odd// frequency elements from an Array // Function that removes the // elements which have odd // frequencies in the array function remove(arr, n) { // Create a map to store the // frequency of each element let mp = new Map(); for (let i = 0; i < n; i++) { if (mp.has(arr[i])) { mp.set(arr[i], mp.get(arr[i]) + 1); } else { mp.set(arr[i], 1); } } // Remove the elements which // have odd frequencies for (let i = 0; i < n; i++) { // If the element has // odd frequency then skip if ((mp.has(arr[i]) && mp.get(arr[i]) % 2 == 1)) continue; document.write(arr[i] + ", "); } } // Driver code let arr = [ 3, 3, 3, 2, 2, 4, 7, 7 ]; let n = arr.length; // Function call remove(arr, n); </script> |
Output
2, 2, 7, 7,
Time Complexity: O(N)
Auxiliary Space: O(N)
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