[LeetCode]Combination Sum II

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

Each number in C may only be used once in the combination.

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 10,1,2,7,6,1,5 and target 8, 
A solution set is: 
[1, 7] 
[1, 2, 5] 
[2, 6] 
[1, 1, 6] 

class Solution {

private:

    vector<vector<int> > ret;

public:

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

    {

        if(sum>target) return;

        else if(sum==target)

        {

            ret.push_back(ans);

        }

        else

        {

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

            {

                ans.push_back(candidates[i]);

                DFS(candidates,i+1,ans,sum+candidates[i],target);

                ans.pop_back();

                while(i<candidates.size()-1&&candidates[i]==candidates[i+1]) i++;

            }

        }

    }

    vector<vector<int> > combinationSum2(vector<int> &candidates, int target) {

        ret.clear();

        vector<int> ans;

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

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

		return ret;

    }

};