# 078-subsets

## Question

https://leetcode.com/problems/subsets/description/

Given a set of distinct integers, nums, return all possible subsets (the power set).

Note:The solution set must not contain duplicate subsets.

Example:

``````If nums = [1,2,3], a solution is:
[
[3],
[1],
[2],
[1,2,3],
[1,3],
[2,3],
[1,2],
[]
]
``````

## Thought Process

1. For creating power set, there are 2^n possibilities, where n is number of elements, due to each element can be either in or out of particular set
2. To help create the set, we can have an additional array

## Solution

``````class Solution {
public List<List<Integer>> subsets(int[] nums) {
List<List<Integer>> res = new ArrayList<>();
backtrack(nums, res, new ArrayList<>(), 0);
return res;
}

public void backtrack(int[] nums, List<List<Integer>> res, List<Integer> path, int start) {
for (int i = start; i < nums.length; i++) {
backtrack(nums, res, path, i + 1);
path.remove(path.size() - 1);
}
}
}
``````
``````class Solution {
public List<List<Integer>> subsets(int[] nums) {
List<List<Integer>> res = new ArrayList<>();
if (nums == null || nums.length == 0) return res;
for (int i = 0; i < nums.length; i++) {
int size = res.size();
for (int j = 0; j < size; j++) {
List<Integer> l = new ArrayList<>(res.get(j));