leetcode week18

Combination Sum

Given a set of candidate numbers (C) (without duplicates) 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.
• 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 {public:    vector<vector<int>> combinationSum(vector<int>& candidates, int target) {        vector<vector<int> > res;        vector<int> out;                sort(candidates.begin(),candidates.end());        combinationSumDFS(candidates,out,0,target,res);        return res;    }    void combinationSumDFS(vector<int>& candidates,vector<int> &out,int start,int target,vector<vector<int> > &res)    {        if(target<0) return;        else if(target == 0) res.push_back(out);        else        {            for(int i =start;i<candidates.size();i++)            {                out.push_back(candidates[i]);                combinationSumDFS(candidates,out,i,target-candidates[i],res);                out.pop_back();            }        }    }    };