Subsets

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.

Code

和 Permutations 的邏輯差不多，差別只在於不需要等到 curr 的 size 和 nums 一樣才將之 push 進 answer，而是每一步都 push。

class Solution {
public:
    vector<vector<int>> subsets(vector<int>& nums) {
        vector<vector<int>> answer;
        vector<int> curr;
        helper(answer, nums, 0, curr);
        return answer;
    }
 
    void helper(vector<vector<int>> &answer, vector<int> nums, int index, vector<int> curr) {
 
        answer.push_back(curr);
 
        for(int i = index; i < nums.size(); i++) {
            curr.push_back(nums[i]);
            // backtracking
            helper(answer, nums, i + 1, curr);
            curr.pop_back();
        }
        
    }
};

Source

• Subsets - LeetCode