LeetCode Online Judge:Given a set of distinct integers, S, return all possible 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],
[]
]

解答：考虑采用递归的思想，先对输入排序，再进行递归

class Solution {
public:
vector<vector<int> > subsets(vector<int> &S) {
int len=S.size();
sort(S.begin(),S.end());
vector<vector<int> > result;
result=test(S,len);
return result;
}
private:
vector<vector<int>> test(vector<int> S,int len)
{
vector<vector<int>> out;
vector<vector<int>> result;
vector<int> tmp;
vector<int> temp;
int elment;
if(len==0)
{
out.push_back(tmp);
return out;
}
else if(len==1)
{
out.push_back(tmp);
tmp.push_back(S[0]);
out.push_back(tmp);
return out;
}
else
{
elment=S[len-1];
out=test(S,len-1);
for(int i=0;i<out.size();i++)
{
result.push_back(out[i]);
temp=out[i];
temp.push_back(elment);
result.push_back(temp);
}
return result;
}
}
};