Product of non-repeating (distinct) elements in an Array

Given an integer array with duplicate elements. The task is to find the product of all distinct elements in the given array.

Examples:

Input : arr[] = {12, 10, 9, 45, 2, 10, 10, 45, 10};
Output : 97200
Here we take 12, 10, 9, 45, 2 for product
because these are the only distinct elements



Input : arr[] = {1, 10, 9, 4, 2, 10, 10, 45, 4};
Output : 32400

A Simple Solution is to use two nested loops. The outer loop picks an element one by one starting from the leftmost element. The inner loop checks if the element is present on the left side of it. If present, then ignores the element.

Time Complexity : O(N2)
Auxiliary Space : O(1)

A Better Solution of this problem is to first sort all elements of the array in ascending order and find one by one distinct element in the array. Finally, find the product of all distinct elements.

Below is the implementation of this approach:

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// C++ program to find the product of all
// non-repeated elements in an array
  
#include <bits/stdc++.h>
using namespace std;
  
// Function to find the product of all
// non-repeated elements in an array
int findProduct(int arr[], int n)
{
    // sort all elements of array
    sort(arr, arr + n);
  
    int prod = 1;
    for (int i = 0; i < n; i++) {
        if (arr[i] != arr[i + 1])
            prod = prod * arr[i];
    }
  
    return prod;
}
  
// Driver code
int main()
{
    int arr[] = { 1, 2, 3, 1, 1, 4, 5, 6 };
    int n = sizeof(arr) / sizeof(int);
  
    cout << findProduct(arr, n);
  
    return 0;
}
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// Java program to find the product of all
// non-repeated elements in an array
import java.util.Arrays;
  
class GFG {
  
// Function to find the product of all
// non-repeated elements in an array
static int findProduct(int arr[], int n)
{
    // sort all elements of array
    Arrays.sort(arr);
      
    int prod = 1 * arr[0];
    for (int i = 0; i < n - 1; i++) 
    {
        if (arr[i] != arr[i + 1]) 
        {
            prod = prod * arr[i + 1];
        }
          
    }
    return prod;
}
  
// Driver code
public static void main(String[] args) {
    int arr[] = {1, 2, 3, 1, 1, 4, 5, 6};
    int n = arr.length;
    System.out.println(findProduct(arr, n));
    }
}
  
// This code is contributed by PrinciRaj1992
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# Python 3 program to find the product 
# of all non-repeated elements in an array
  
# Function to find the product of all
# non-repeated elements in an array
def findProduct(arr, n):
      
    # sort all elements of array
    sorted(arr)
  
    prod = 1
    for i in range(0, n, 1):
        if (arr[i - 1] != arr[i]):
            prod = prod * arr[i]
  
    return prod;
  
# Driver code
if __name__ == '__main__':
    arr = [1, 2, 3, 1, 1, 4, 5, 6]
  
    n = len(arr)
  
    print(findProduct(arr, n))
  
# This code is contributed by 
# Surendra_Gangwar
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// C# program to find the product of all
// non-repeated elements in an array
using System;
  
class GFG 
{
  
// Function to find the product of all
// non-repeated elements in an array
static int findProduct(int []arr, int n)
{
    // sort all elements of array
    Array.Sort(arr);
      
    int prod = 1 * arr[0];
    for (int i = 0; i < n - 1; i++) 
    {
        if (arr[i] != arr[i + 1]) 
        {
            prod = prod * arr[i + 1];
        }
          
    }
    return prod;
}
  
// Driver code
public static void Main() 
{
    int []arr = {1, 2, 3, 1, 1, 4, 5, 6};
    int n = arr.Length;
    Console.WriteLine(findProduct(arr, n));
}
}
  
// This code is contributed by 29AjayKumar
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Output:
720

Time Complexity : O(N * logN)
Auxiliary Space : O(1)

An Efficient Solution is to traverse the array and keep a hash map to check if the element is repeated or not. While traversing if the current element is already present in the hash or not, if yes then it means it is repeated and should not be multiplied with the product, if it is not present in the hash then multiply it with the product and insert it into hash.

Below is the implementation of this approach:

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// C++ program to find the product of all
// non- repeated elements in an array
#include <bits/stdc++.h>
using namespace std;
  
// Function to find the product of all
// non-repeated elements in an array
int findProduct(int arr[], int n)
{
    int prod = 1;
  
    // Hash to store all element of array
    unordered_set<int> s;
    for (int i = 0; i < n; i++) {
        if (s.find(arr[i]) == s.end()) {
            prod *= arr[i];
            s.insert(arr[i]);
        }
    }
  
    return prod;
}
  
// Driver code
int main()
{
    int arr[] = { 1, 2, 3, 1, 1, 4, 5, 6 };
    int n = sizeof(arr) / sizeof(int);
  
    cout << findProduct(arr, n);
  
    return 0;
}
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// Java program to find the product of all
// non- repeated elements in an array
import java.util.HashSet;
  
class GFG 
{
  
    // Function to find the product of all
    // non-repeated elements in an array
    static int findProduct(int arr[], int n)
    {
        int prod = 1;
  
        // Hash to store all element of array
        HashSet<Integer> s = new HashSet<>();
        for (int i = 0; i < n; i++) 
        {
            if (!s.contains(arr[i])) 
            {
                prod *= arr[i];
                s.add(arr[i]);
            }
        }
  
        return prod;
    }
  
    // Driver code
    public static void main(String[] args) 
    {
        int arr[] = {1, 2, 3, 1, 1, 4, 5, 6};
        int n = arr.length;
  
        System.out.println(findProduct(arr, n));
    }
}
  
/* This code contributed by PrinciRaj1992 */
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# Python3 program to find the product of all
# non- repeated elements in an array
  
# Function to find the product of all
# non-repeated elements in an array
def findProduct( arr, n):
  
    prod = 1
  
    # Hash to store all element of array
    s = dict()
    for i in range(n):
        if (arr[i] not in s.keys()):
            prod *= arr[i]
            s[arr[i]] = 1
      
    return prod
  
# Driver code
arr= [1, 2, 3, 1, 1, 4, 5, 6
n = len(arr)
  
print(findProduct(arr, n))
  
# This code is contributed by mohit kumar
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// C# program to find the product of all
// non- repeated elements in an array
using System;
using System.Collections.Generic; 
      
class GFG 
{
  
    // Function to find the product of all
    // non-repeated elements in an array
    static int findProduct(int []arr, int n)
    {
        int prod = 1;
  
        // Hash to store all element of array
        HashSet<int> s = new HashSet<int>();
        for (int i = 0; i < n; i++) 
        {
            if (!s.Contains(arr[i])) 
            {
                prod *= arr[i];
                s.Add(arr[i]);
            }
        }
  
        return prod;
    }
  
    // Driver code
    public static void Main(String[] args) 
    {
        int []arr = {1, 2, 3, 1, 1, 4, 5, 6};
        int n = arr.Length;
  
        Console.WriteLine(findProduct(arr, n));
    }
}
  
// This code is contributed by Princi Singh
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Output:
720

Time Complexity : O(N)
Auxiliary Space: O(N)




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