【leetcode】Subsets

Subsets

Given a set of distinct integers, S, return all possible subsets.

Note:

• Elements in a subset must be in non-descending order.
• The solution set must not contain duplicate subsets.

For example,
If S = [1,2,3], a solution is:

[
  [3],
  [1],
  [2],
  [1,2,3],
  [1,3],
  [2,3],
  [1,2],
  []
]

采用递归，取当前元素，或者不取当前元素。

 1 class Solution {
 2
 3 public:
 4
 5     vector<vector<int> > subsets(vector<int> &S) {
 6
 7
 8
 9         vector<vector<int> > result;
10
11         vector<int> tmp;
12
13         sort(S.begin(),S.end());
14
15         getSubset(result,S,0,tmp);
16
17         return result;
18
19     }
20
21
22
23     void getSubset(vector<vector<int> > &result,vector<int> &S,int index,vector<int> tmp)
24
25     {
26
27         if(index==S.size())
28
29         {
30
31             result.push_back(tmp);
32
33             return;
34
35         }
36
37
38
39         getSubset(result,S,index+1,tmp);
40
41         tmp.push_back(S[index]);
42
43         getSubset(result,S,index+1,tmp);
44
45
46
47     }
48
49 };