Subsets II

Given a collection of integers that might contain duplicates, 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 = [1,2,2], a solution is:

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

class Solution {
public:
    vector<vector<int> > subsetsWithDup(vector<int> &S) {
        sort(S.begin(), S.end());
        vector<vector<int>> ret = {{}};
        int size = 0, startIndex = 0;
        for (int i = 0; i < S.size(); i++) {
            startIndex = i >= 1 && S[i] == S[i - 1] ? size : 0;
            size = ret.size();
            for (int j = startIndex; j < size; j++) {
                vector<int> temp = ret[j];
                temp.push_back(S[i]);
                ret.push_back(temp);
            }
        }
        return ret;
    }
};