78. Subsets 🌟🌟

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.

Recursive solution

• For a number we have 2 choices: either we can include it OR not in include it.

code

class Solution {
public:
void subsets_helper(vector<int>& nums, vector<int>& output, int index, vector<vector<int>>& ans)
{
    if (index >= nums.size()) {
        ans.push_back(output);
        return;
    }

    // include
    output.push_back(nums[index]);
    subsets_helper(nums, output, index + 1, ans);

    // exclude
    output.pop_back();
    subsets_helper(nums, output, index + 1, ans);
}

vector<vector<int>> subsets(vector<int>& nums)
{
    vector<vector<int>> ans;
    vector<int> res;
    int index = 0;
    subsets_helper(nums, res, index, ans);
    return ans;
}
};