78. Subsets

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LeetCode

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Problem

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

Note: The solution set must not contain duplicate subsets.

Example:

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

Code

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

    private void helper(List<List<Integer>> res, int[] nums, int index, List<Integer> temp){
        res.add(new ArrayList<Integer>(temp));

        for(int i = index; i < nums.length; i++){
            temp.add(nums[i]);
            helper(res, nums, i + 1, temp);
            temp.remove(temp.size() - 1);
        }
    }
}