[LeetCode] Problem 78 - Subsets

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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:

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

Code

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public List<List<Integer>> subsets(int[] nums) {
    List<List<Integer>> result = new ArrayList<>();

    subsetsHelper(result, new ArrayList<>(), nums, 0);
    return result;
}

private void subsetsHelper(List<List<Integer>> result, List<Integer> subset, int[] nums, int idx) {
    result.add(new ArrayList<>(subset));

    for (int i = idx; i < nums.length; i++) {
        subset.add(nums[i]);
        subsetsHelper(result, subset, nums, i + 1);
        subset.remove(subset.size() - 1);
    }
}