LeetCode: Permutations II [046]

class Solution {
public:
    void permute(vector<vector<int> >&result, vector<int>combination, vector<int>candidates, int index2remove){
        //combination——当前已生成的组合
        //candidates——候选数字集合
        //index2remove——添加到combination的下一个数字在candidates中的索引位
        combination.push_back(candidates[index2remove]);
        candidates.erase(candidates.begin()+index2remove);
        if(candidates.empty()){
            result.push_back(combination);
        }
        else{
            for(int i=0; i<candidates.size(); i++){
                if(i!=0 && candidates[i]==candidates[i-1])continue; //去重
                permute(result, combination, candidates, i);
            }
        }
    }

    vector<vector<int> > permuteUnique(vector<int> &num) {
        vector<vector<int> >result;
        int size=num.size();
        if(size==0)return result;
        sort(num.begin(), num.end()); //先排序，便于排重
        vector<int>combination;
        for(int i=0; i<size; i++){
            if(i!=0 && num[i]==num[i-1])continue;   //去重
            permute(result, combination, num, i);
        }
        return result;
    }
};