01 Powerset

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LeetCode: Subset

Question

Given an integer array nums of unique elements, return all possible subsets (the power set).

The solution set must not contain duplicate subsets. Return the solution in any order.

Example 1:

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

Example 2:

Input: nums = [0]
Output: [[],[0]]

Constraints:

• 1 <= nums.length <= 10

• -10 <= nums[i] <= 10

• All the numbers of nums are unique.

Using DFS

Logic

1. In every recursive call either include or exclude an element.

Code

typedef vector<int> vi;
typedef vector<vi> vvi;

vvi res;

void getSubsets(const vi &nums, int i, vi &subset) {
    if(i == nums.size())
        res.push_back(subset);
    else {
        getSubsets(nums, i + 1, subset);
        subset.push_back(nums[i]);       
        getSubsets(nums, i + 1, subset);
        subset.pop_back();
    }
}

vvi subsets(vi& nums) {
    vi *subset = new vector<int>;
    getSubsets(nums, 0, *subset);
    delete subset;
    return res;
}