90 Subsets II

Given a collection of integers that might contain duplicates, nums, return all possible subsets.

Note: The solution set must not contain duplicate subsets.

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

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

Solution:

class Solution {
public:
    vector<vector<int>> subsetsWithDup(vector<int>& nums) {
        vector<vector<int>> res;
        vector<int> tmp;
        res.push_back(tmp);
        sort(nums.begin(), nums.begin()+nums.size());
        int i = 0;
        while ( i <= nums.size()-1 ) {
            int icount = 0, ni = nums[i];
            while ( i <= nums.size()-1 and nums[i] == ni ) {
                icount += 1;
                i += 1;
            }
            int nres = res.size();
            for ( int j = 0; j <= nres-1; j++ ) {
                tmp = res[j];
                for ( int k = 1; k <= icount; k++ ) {
                    tmp.push_back(ni);
                    res.push_back(tmp);
                }
            }
        }
        return res;
    }
};

Note: sort an array in C++:

sort(nums.begin(), nums.begin()+nums.size());