# Product of all Subarrays of an Array

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, 4], 
Prodcuts are 2, 8, 4
Product of all Subarrays = 64

Input : arr[] = {10, 3, 7}
Output : 30870
Here, subarrays are , [10, 3], [10, 3, 7], , [3, 7], 
Prodcuts are 10, 30, 210, 3, 21, 7
Product of all Subarrays = 27783000

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

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 ` `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[j]; ` `        ``} ` `    ``} ` ` `  `    ``// Printing product of all subarray ` `    ``cout << product << ``"\n"``; ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` `    ``int` `arr[] = { 10, 3, 7 }; ` ` `  `    ``int` `n = ``sizeof``(arr) / ``sizeof``(arr); ` ` `  `    ``// 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[j]; ` `       ``} ` `    ``} ` ` `  `    ``// 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[j]; ` `         `  `    ``# 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[j]; ` `       ``} ` `    ``} ` ` `  `    ``// 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 `

Output:

```31765230
```

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 ` `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); ` ` `  `    ``// 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:

```30870
```

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