Given a set of distinct integers, S, return all possible subsets.
Note:
For example,
If S = [1,2,3], a solution is:
[ [3], [1], [2], [1,2,3], [1,3], [2,3], [1,2], [] ]
1 class Solution { 2 public: 3 vector<vector<int> > subsets(vector<int> &S) { 4 vector<vector<int>> res; 5 vector<int> empty; 6 res.push_back(empty); 7 8 int len = S.size(); 9 if(len == 0) return res; 10 sort(S.begin(),S.end()); 11 for(int k = 1; k <= len; k++){ 12 vector<int> path; 13 for(int i = 0; i < len; i++) 14 get_subsets(S,res,path,i,k,1); 15 } 16 return res; 17 } 18 void get_subsets(vector<int> & S, vector<vector<int>> & res, vector<int> & path, int start,int k, int l){ 19 path.push_back(S[start]); 20 if(l == k) res.push_back(path); 21 for(int i = start+1; i < S.size(); i++){ 22 get_subsets(S,res,path,i,k,l+1); 23 } 24 path.pop_back(); 25 } 26 };
原文：http://www.cnblogs.com/Kai-Xing/p/3906165.html