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]] Solution:  回溯法

class Solution {public:        void combination(vector
     
      & candidates, int target,vector
      
       & tmp,vector
       
        
         >& myvec,int start){        if(!target){            myvec.push_back(tmp);            return;        }        for(int i=start;i
         
          <=target;i++){            tmp.push_back(candidates[i]);            combination(candidates,target-candidates[i],tmp,myvec,i);            tmp.pop_back();        }            }    vector
          
           
            > combinationSum(vector
            
             & candidates, int target) { vector
             
              
               > myvec; sort(candidates.begin(),candidates.end()); vector
               
                 tmp; combination(candidates,target,tmp,myvec,0); return myvec; }};