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;
    }
};