[LeetCode]Combination Sum

Given a set of candidate numbers (C) and a target number (T), find all unique combinations in C where the candidate numbers sums to T.

The same repeated number may be chosen from C unlimited number of times.

Note:

• All numbers (including target) will be positive integers.
• Elements in a combination (a₁, a₂, … , a_k) must be in non-descending order. (ie, a₁ ≤ a₂ ≤ … ≤ a_k).
• The solution set must not contain duplicate combinations.

 

For example, given candidate set 2,3,6,7 and target 7, 
A solution set is: 
[7] 
[2, 2, 3] 

class Solution {

private:

    vector<vector<int> > ret;

public:

    void DFS(vector<int> &candidates,int dep,vector<int> ans,int sum,int target)

    {

        ans.push_back(candidates[dep]);

        sum+=candidates[dep];

        if(sum==target) 

        {

            ret.push_back(ans);

        }

        else if(sum<target)

        {

            for(int i=dep;i<candidates.size();i++)

            DFS(candidates,i,ans,sum,target);

        }

        else 

        {

            return;

        }

    }

    vector<vector<int> > combinationSum(vector<int> &candidates, int target) {

        ret.clear();

        vector<int> ans;

		sort(candidates.begin(),candidates.end());

		for(int i=0;i<candidates.size();i++)

		DFS(candidates,i,ans,0,target);

		return ret;

    }

};