Permutations II

class Solution {
public:

    vector<vector<int> > res;
    
    void search(vector<int>& num, vector<int>& cur)
    {
        if (num.empty())
        {
            res.push_back(cur);
            return;
        }
        
        int prev = 0, len = num.size();
    
        for (int i=0; i<len; ++i)
        {
            if (i>0 && num[i]==prev)
                continue;
            else
            {
                prev = num[i];
                cur.push_back(num[i]);
                num.erase(num.begin()+i);
                search(num, cur);
                num.insert(num.begin()+i, prev);
                cur.pop_back();
            }
        }
    }
    
    vector<vector<int> > permuteUnique(vector<int> &num) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        res.clear();
        sort(num.begin(), num.end());
        
        vector<int> tmp;
        search(num, tmp);
        return res;
    }
};