leetcode_combination_sum_ii

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难度：Medium

解题思路：是CombinationSum系列。不重复使用元素就可以了。
代码如下：

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class Solution {
public:
    vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {
        sort(candidates.begin(), candidates.end());
        vector<vector<int>> ret;
        vector<int> cur_vec;
        combination_sum_recur(ret,candidates,target,0,cur_vec);
        return ret;
    }
    void combination_sum2_recur(vector<vector<int>> &ret, vector<int>& candidates, int target, int index, vector<int>& cur_vec)
    {
        if(target == 0)
        {
            ret.push_back(cur_vec);
        }
        else if(target > 0)
        {
            for(int i = index; i < candidates.size(); i++)
            {
                if(i-1 >= index && candidates[i-1] == candidates[i])
                    continue;
                cur_vec.push_back(candidates[i]);
                combination_sum_recur(ret,candidates,target-candidates[i],i+1,cur_vec);
                cur_vec.pop_back();
            }
        }
        
    }
};

运行结果：16ms，超过36.98%