Problem

Problem 78

Given a set of distinct integers, nums, return all possible subsets (the power set).

Note: The solution set must not contain duplicate subsets.

面试题 08.04

Write a method to return all subsets of a set. The elements in a set are pairwise distinct.

Note: The result set should not contain duplicated subsets.

Solution

首先画出搜索树，/之前表示当前的结果，/之后表示可以做的选择。

class Solution {
public:
    vector<vector<int>> subsets(vector<int>& nums) {
        vector<vector<int>> ret;
        vector<int> tmp;
        backtrack(nums,tmp,0,ret);
        return ret;

    }

    void backtrack(vector<int>& nums,vector<int>& tmp,int begin,vector<vector<int>> &ret)
    {
        ret.push_back(tmp);
        
        for(int i = begin;i<nums.size();++i)
        {
            
            tmp.push_back(nums[i]);
            backtrack(nums,tmp,i+1,ret);
            tmp.pop_back();

        }
    }
};