LeetCode78. Subsets

一、题目

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.

二、题解

在树的每个节点都收获结果，而不是像组合问题那样在叶子结点收获结果。

class Solution {
public:
    vector<vector<int>> res;
    vector<int> path;
    void backtracking(vector<int>& nums,int startIndex){
        res.push_back(path);
        if(startIndex == nums.size()) return;
        for(int i = startIndex;i < nums.size();i++){
            path.push_back(nums[i]);
            backtracking(nums,i + 1);
            path.pop_back();
        }
    }
    vector<vector<int>> subsets(vector<int>& nums) {
        backtracking(nums,0);
        return res;
    }
};