LEETCODE: 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],  []]

思路同LEETCODE: Combinations

class Solution {public:    vector<vector<int> > subsets(vector<int> &S) {        vector<vector<int> > results;        results.push_back(vector<int>());        if(S.size() == 0) return results;        sort(S.begin(), S.end());        for(int ii = 1; ii <= S.size(); ii ++) {            vector<int> current;            for(int jj = 0; jj < ii; jj ++) {                current.push_back(S[jj]);            }            while(current.size() == ii) {                results.push_back(current);                int pos = ii - 1;                while(pos >= 0) {                    if(current[pos] < S[S.size() - 1]) {                        int kk = 0;                        for(; kk < S.size(); kk ++) {                            if(S[kk] == current[pos])                                break;                        }                        if(ii - 1 - pos < S.size() - 1 - kk)                            break;                    }                        pos --;                }                if(pos < 0)                    break;                                int posins = 0;                while(posins < S.size()) {                    if(current[pos] == S[posins])                        break;                    posins ++;                }                                posins ++;                                for(int kk = pos; kk < current.size(); kk ++) {                    current[kk] = S[posins++];                }            }        }                return results;    }};