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78. Subsets

Difficulty Topics

Description

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.

Solution

subsets.py
class Solution:
    def subsets(self, nums: List[int]) -> List[List[int]]:
        res = []
        seen = set()
        n = len(nums)

        for mask in range(1 << n):
            h = 0
            curr = []

            for j in range(n):
                if mask & (1 << j) > 0:
                    curr.append(nums[j])
                    h |= (1 << j)

            if h not in seen:
                res.append(curr)
                seen.add(h)

        return res
subsets.cpp
class Solution {
public:
    vector<vector<int>> subsets(vector<int>& nums) {
        int n = nums.size();
        vector<vector<int>> res;

        for (int i=0; i < 1<<n; ++i){
            vector<int> c;
            for (int j = 0; j < n; ++j)
                if (i >> j&1)
                    c.push_back(nums[j]);
            res.push_back(c);
        }

        return res;
    }
};