leetcode 78.子集

这道题可以DFS，代码如下，很好理解

class Solution {
public:
    void dfs(int index,int n,vector<int> tmp,vector<int>& nums,vector<vector<int>>& ans){
        if(index==n){
            ans.push_back(tmp);
            return;}
            tmp.push_back(nums[index]);//选当前索引的数字
            dfs(index+1,n,tmp,nums,ans);
            tmp.pop_back();//不选当前索引的数字
            dfs(index+1,n,tmp,nums,ans);
    }
    vector<vector<int>> subsets(vector<int>& nums) {
        vector<vector<int>> ans;
        vector<int> tmp;
        dfs(0,nums.size(),tmp,nums,ans);
        return ans;
    }
};

结果