Combination Sum(组合总和)

题目：链接

代码

class Solution 
{
private:
    vector<vector<int>> rems;
public:
    vector<vector<int>> combinationSum(vector<int>& candidates, int target) 
    {
        sort(candidates.begin(), candidates.end());
        vector<int> rets;
        backtracking(candidates, target, rets, 0);
        return rems;        
    }

    void backtracking(vector<int> &candidates, int target, vector<int> &rets, int start)
    {
        if(target == 0)
        {

            rems.push_back(rets);
            return;
        }
        if(target < 0)
            return;
        for(int i = start; i < candidates.size(); ++i)
        {
            rets.push_back(candidates[i]);
            backtracking(candidates, target-candidates[i],  rets, i);
            rets.pop_back();
        }
    }
};