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Product of all Subarrays of an Array
  • Difficulty Level : Medium
  • Last Updated : 22 Mar, 2021

Given an array of integers arr of size N, the task is to print products of all subarrays of the array.
Examples: 
 

Input: arr[] = {2, 4} 
Output: 64 
Here, subarrays are [2], [2, 4], [4] 
Products are 2, 8, 4 
Product of all Subarrays = 64
Input : arr[] = {10, 3, 7} 
Output : 27783000 
Here, subarrays are [10], [10, 3], [10, 3, 7], [3], [3, 7], [7] 
Prodcuts are 10, 30, 210, 3, 21, 7 
Product of all Subarrays = 27783000 
 

 

Naive Approach: A simple solution is to generate all sub-array and compute their product.
 

C++




// C++ program to find product
// of all subarray of an array
 
#include <bits/stdc++.h>
using namespace std;
 
// Function to find product of all subarrays
void product_subarrays(int arr[], int n)
{
    // Variable to store the product
    int product = 1;
 
    // Compute the product while
    // traversing for subarrays
    for (int i = 0; i < n; i++) {
        for (int j = i; j < n; j++) {
            for (int k = i; k <= j; k++)
                product *= arr[k];
        }
    }
 
    // Printing product of all subarray
    cout << product << "\n";
}
 
// Driver code
int main()
{
    int arr[] = { 10, 3, 7 };
 
    int n = sizeof(arr) / sizeof(arr[0]);
 
    // Function call
    product_subarrays(arr, n);
 
    return 0;
}

Java




// Java program to find product
// of all subarray of an array
import java.util.*;
 
class GFG {
 
    // Function to find product of all subarrays
    static void product_subarrays(int arr[], int n)
    {
 
        // Variable to store the product
        int product = 1;
 
        // Compute the product while
        // traversing for subarrays
        for (int i = 0; i < n; i++) {
            for (int j = i; j < n; j++) {
                for (int k = i; k <= j; k++)
                    product *= arr[k];
            }
        }
 
        // Printing product of all subarray
        System.out.print(product + "\n");
    }
 
    // Driver code
    public static void main(String args[])
    {
        int arr[] = { 10, 3, 7 };
        int n = arr.length;
 
        // Function call
        product_subarrays(arr, n);
    }
}
 
// This code is contributed by shivanisinghss2110

Python3




# Python3 program to find product
# of all subarray of an array
 
# Function to find product of all subarrays
def product_subarrays(arr, n):
 
    # Variable to store the product
    product = 1;
 
    # Compute the product while
    # traversing for subarrays
    for i in range(0, n):
        for j in range(i, n):
            for k in range(i, j + 1):
                product *= arr[k];
         
    # Printing product of all subarray
    print(product, "\n");
 
# Driver code
arr = [ 10, 3, 7 ];
 
n = len(arr);
 
# Function call
product_subarrays(arr, n);
 
# This code is contributed by Code_Mech

C#




// C# program to find product
// of all subarray of an array
using System;
 
class GFG {
 
    // Function to find product of all subarrays
    static void product_subarrays(int[] arr, int n)
    {
 
        // Variable to store the product
        int product = 1;
 
        // Compute the product while
        // traversing for subarrays
        for (int i = 0; i < n; i++) {
            for (int j = i; j < n; j++) {
                for (int k = i; k <= j; k++)
                    product *= arr[k];
            }
        }
 
        // Printing product of all subarray
        Console.Write(product + "\n");
    }
 
    // Driver code
    public static void Main(String[] args)
    {
        int[] arr = { 10, 3, 7 };
        int n = arr.Length;
 
        // Function call
        product_subarrays(arr, n);
    }
}
 
// This code is contributed by shivanisinghss2110

Javascript




<script>
  // Javascript program to find product
  // of all subarray of an array
   
  // Function to find product of all subarrays
  function product_subarrays(arr, n)
  {
   
      // Variable to store the product
      let product = 1;
 
      // Compute the product while
      // traversing for subarrays
      for (let i = 0; i < n; i++) {
          for (let j = i; j < n; j++) {
              for (let k = i; k <= j; k++)
                  product *= arr[k];
          }
      }
 
      // Printing product of all subarray
      document.write(product + "</br>");
  }
   
  let arr = [ 10, 3, 7 ];
  let n = arr.length;
 
  // Function call
  product_subarrays(arr, n);
 
// This code is contributed by divyeshrabadiya07.
</script>
Output: 



27783000

 

Efficient Approach: An efficient approach is to use two loops and calculate the products while traversing for the subarrays.
Below is the implementation of the above approach: 
 

C++




// C++ program to find product
// of all subarray of an array
 
#include <bits/stdc++.h>
using namespace std;
 
// Function to find product of all subarrays
void product_subarrays(long long int arr[], int n)
{
    // Variable to store the product
    long long int res = 1;
 
    // Compute the product while
    // traversing for subarrays
    for (int i = 0; i < n; i++) {
        long long int product = 1;
        for (int j = i; j < n; j++) {
            product = product * arr[j];
            res *= product;
        }
    }
    // Printing product of all subarray
    cout << res << "\n";
}
 
// Driver code
int main()
{
    long long int arr[] = { 10, 3, 7 };
 
    int n = sizeof(arr) / sizeof(arr[0]);
 
    // Function call
    product_subarrays(arr, n);
 
    return 0;
}

Java




// Java program to find product
// of all subarray of an array
import java.util.*;
 
class GFG {
 
    // Function to find product of all subarrays
    static void product_subarrays(int arr[], int n)
    {
        // Variable to store the product
        int res = 1;
 
        // Compute the product while
        // traversing for subarrays
        for (int i = 0; i < n; i++) {
            int product = 1;
            for (int j = i; j < n; j++) {
                product = product * arr[j];
                res *= product;
            }
        }
 
        // Printing product of all subarray
        System.out.println(res + "\n");
    }
 
    // Driver code
    public static void main(String args[])
    {
        int arr[] = { 10, 3, 7 };
 
        int n = arr.length;
 
        // Function call
        product_subarrays(arr, n);
    }
}
 
// This code is contributed by AbhiThakur

Python3




# Python3 program to find product
# of all subarray of an array
 
# Function to find product of all subarrays
def product_subarrays(arr, n):
 
    # Variable to store the product
    res = 1;
 
    # Compute the product while
    # traversing for subarrays
    for i in range(n):
        product = 1
        for j in range(i, n):
            product *= arr[j];
            res = res * product
 
    # Printing product of all subarray
    print(res);
 
# Driver code
if __name__ == '__main__':
    arr = [ 10, 3, 7 ];
 
    n = len(arr);
 
    # Function call
    product_subarrays(arr, n);
 
# This code is contributed by Princi Singh

C#




// C# program to find product
// of all subarray of an array
using System;
 
class GFG {
 
    // Function to find product of all subarrays
    static void product_subarrays(int[] arr, int n)
    {
        // Variable to store the product
        int res = 1;
 
        // Compute the product while
        // traversing for subarrays
        for (int i = 0; i < n; i++) {
            int product = 1;
            for (int j = i; j < n; j++) {
                product *= arr[j];
                res = res * product;
            }
        }
 
        // Printing product of all subarray
        Console.WriteLine(res + "\n");
    }
 
    // Driver code
    public static void Main(String[] args)
    {
        int[] arr = { 10, 3, 7 };
 
        int n = arr.Length;
 
        // Function call
        product_subarrays(arr, n);
    }
}
 
// This code is contributed by 29AjayKumar
Output: 
27783000

 

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