# Number of distinct subsets of a set

Given an array of n distinct elements, count total number of subsets.

Examples:

```Input : {1, 2, 3}
Output : 8
Explanation
the array contain total 3 element.its subset
are {}, {1}, {2}, {3}, {1, 2}, {2, 3}, {3, 1}, {1, 2, 3}.
so the output is 8..
```

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

We know number of subsets of set of size n is 2n
How does this formula work?
For every element, we have two choices, we either pick it or do not pick it. So in total we have 2 * 2 * … (n times) choices which is 2n

Alternate explanation is :
Number of subsets of size 0 = nC0
Number of subsets of size 1 = nC1
Number of subsets of size 2 = nC2
………………..

Total number of subsets = nC0 + nC1 + nC2 + …. + nCn = 2n

Please refer Sum of Binomial Coefficients for details.

## C++

 `// CPP program to count number of distinct ` `// subsets in an array of distinct numbers ` `#include ` `using` `namespace` `std; ` ` `  `// Returns 2 ^ n ` `int` `subsetCount(``int` `arr[], ``int` `n) ` `{ ` `    ``return` `1 << n; ` `} ` ` `  `/* Driver program to test above function */` `int` `main() ` `{ ` `    ``int` `A[] = { 1, 2, 3 }; ` `    ``int` `n = ``sizeof``(A) / ``sizeof``(A); ` ` `  `    ``cout << subsetCount(A, n); ` `    ``return` `0; ` `} `

## Java

 `// Java program to count number of distinct ` `// subsets in an array of distinct numbers ` ` `  `class` `GFG { ` `     `  `    ``// Returns 2 ^ n ` `    ``static` `int` `subsetCount(``int` `arr[], ``int` `n) ` `    ``{ ` `        ``return` `1` `<< n; ` `    ``} ` `     `  `    ``/* Driver program to test above function */` `    ``public` `static` `void` `main(String[] args) ` `    ``{ ` `        ``int` `A[] = { ``1``, ``2``, ``3` `}; ` `        ``int` `n = A.length; ` `     `  `        ``System.out.println(subsetCount(A, n)); ` `    ``} ` `} ` ` `  `// This code is contributed by Prerna Saini. `

## Python3

 `# Python3 program to count number  ` `# of distinct subsets in an ` `# array of distinct numbers ` `import` `math ` ` `  `# Returns 2 ^ n ` `def` `subsetCount(arr, n): ` ` `  `    ``return` `1` `<< n ` `     `  `# driver code  ` `A ``=` `[ ``1``, ``2``, ``3` `] ` `n ``=` `len``(A) ` `print``(subsetCount(A, n)) ` ` `  `# This code is contributed by Gitanjali. `

## C#

 `// C# program to count number of distinct ` `// subsets in an array of distinct numbers ` `using` `System; ` ` `  `class` `GFG { ` `     `  `    ``// Returns 2 ^ n ` `    ``static` `int` `subsetCount(``int` `[]arr, ``int` `n) ` `    ``{ ` `        ``return` `1 << n; ` `    ``} ` `     `  `    ``// Driver program  ` `    ``public` `static` `void` `Main() ` `    ``{ ` `        ``int` `[]A = { 1, 2, 3 }; ` `        ``int` `n = A.Length; ` `     `  `        ``Console.WriteLine(subsetCount(A, n)); ` `    ``} ` `} ` ` `  `// This code is contributed by vt_m. `

## PHP

 ` `

Output:

```8
```

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