78. Subsets

Problem Statement

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.

Intuition

Approach:

Power Set Method(Bit MAsking)

Links

https://leetcode.com/problems/subsets/description/

Video Links

https://www.youtube.com/watch?v=b7AYbpM5YrE&ab_channel=takeUforward

Approach 1:

C++

class Solution {
public:
    void gen_sets(vector<int>& nums, int index, int n, vector<vector<int>> &a, 
                    vector<int> &temp){

        if(index==n){
            a.push_back(temp);
            return ;
        }

        gen_sets(nums,index+1,n,a,temp);
        temp.push_back(nums[index]);
        gen_sets(nums,index+1,n,a,temp);
        temp.pop_back();
    }

    vector<vector<int>> subsets(vector<int>& nums) {
        vector<vector<int>>a;
        vector<int>temp;
        gen_sets(nums,0,nums.size(),a,temp);

        return a;
    }
};

Approach 2:

C++

class Solution {
public:
    vector<vector<int>> subsets(vector<int>& nums) {
        int n = nums.size();
        vector<vector<int>> ans;
        for(int i=0; i<(1<<n); i++){
            vector<int> temp;
            
            for(int j=0; j<n; j++){
                if(i & (1<<j))
                    temp.push_back(nums[j]);
            }

            ans.push_back(temp);
        }

        return ans;
    }
};

Approach 3:

C++

Approach 4:

C++