Program for Power set of a given array of integers

Overview

An integer array is given which has all unique elements. The objective is to return the power set of that array

Input: [1, 2]
Output: [[],[1],[2],[1,2]]

Input: [1, 2, 3]
Output: [[] [1] [2] [1 2] [3] [1 3] [2 3] [1 2 3]]

If the number of elements in the given array is n, then the number of elements in the power set will be pow(2, n). Let’s say n is 3  then the number of elements in the power set will be pow(2, n)=8

Let’s say we take all binary conversion of numbers from 0 to (8-1) ie from 0 to 7.

000
001
010
011
100
101
110
111

Each of the binary numbers above represents a power set

Eg

000 - []
001 - [1]
010 - [2]
011 - [1, 2]
100 - [3]
101 - [1, 3]
110 - [2, 3]
111 - [1, 2, 3]

Program

Here is the program for the same.

package main

import (
	"fmt"
	"math"
)

func subsets(nums []int) [][]int {

	lengthNums := len(nums)
	powerSetLength := int(math.Pow(2, float64(lengthNums)))
	output := make([][]int, 0)

	for i := 0; i < powerSetLength; i++ {

		result := make([]int, 0)
		for j := 0; j < lengthNums; j++ {
			val := int(i) & int(1<<j)
			if val != 0 {
				result = append(result, nums[j])
			}
		}

		output = append(output, result)
	}

	return output
}

func main() {
	output := subsets([]int{1, 2})
	fmt.Println(output)

	output = subsets([]int{1, 2, 3})
	fmt.Println(output)
}

Output

[[] [1] [2] [1 2]]
[[] [1] [2] [1 2] [3] [1 3] [2 3] [1 2 3]]