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 array void 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 code int 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 Array import 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 Array using 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)