Description

Given a set of distinct integers, nums, return all possible subsets.

Note: The solution set must not contain duplicate subsets.

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

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

Solution

DFS

class Solution {
    public List<List<Integer>> subsets(int[] nums) {
        List<List<Integer>> subsets = new LinkedList<>();
        if (nums == null || nums.length < 1) {
            return subsets;
        }
        
        subsetsRecur(0, nums, new LinkedList<>(), subsets);
        return subsets;
    }
    
    public void subsetsRecur(int i, int[] nums, List<Integer> subset
                             , List<List<Integer>> subsets) {
        if (i == nums.length) {
            subsets.add(new LinkedList<>(subset));
            return;
        }
        
        subsetsRecur(i + 1, nums, subset, subsets);
        subset.add(nums[i]);
        subsetsRecur(i + 1, nums, subset, subsets);
        subset.remove(subset.size() - 1);
    }
}