LeetCode 78. subset

Title Description

78. A subset of

solution

The permutation and combination problems involved in programming are inseparable from backtracking , Below we post a pseudo code about backtracking , With this backtracking framework , Combined with the backtracking tree, it is easy to understand

result = []

def backtrack( route ,  Selection list ):
	if  Meet the end condition :
		result.add( route )
		return
	for  choice  in  Selection list :
		 To make a choice 
		backtrack( route , Selection list )
		 Unselect 

class Solution {
    
public:
    vector<vector<int>> res;
    vector<vector<int>> subsets(vector<int>& nums) {
    
        vector<int> track;
        backtrace(nums, 0, track);
        return res;
    }

    void backtrace(vector<int>& nums, int start, vector<int>& track){
    
        res.push_back(track);
        for (int i = start; i <  nums.size(); i++)
        {
    
            track.push_back(nums[i]);
            backtrace(nums, i + 1, track);
            track.pop_back();
        }
    }
};