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]

 

需要把子过程的结果存储起来

class Solution {public:   void sub(vector
      
       & c,int len,int target ,        map
       
        
         ,vector
         
          
            > > &m1){                if(m1.find(pair
           
            (len,target))!=m1.end()){ return; } else{ if(target==0){ m1[pair
            
             (len,target)]=vector
             
              
                >(1); return; } if(len==1){ if(target%c[0]==0){ vector
               
                
                 >& vec=m1[pair
                 
                  (len,target)]; vec.resize(1); for(int j=0;j
                  
                   target){ sub(c,len-1,target,m1); m1[pair
                   
                    (len,target)]=m1[pair
                    
                     (len-1,target)]; return; } else{ sub(c,len-1,target,m1); m1[pair
                     
                      (len,target)]=m1[pair
                      
                       (len-1,target)]; vector
                       
                        
                         >& vec=m1[pair
                         
                          (len,target)]; for(int i=1;i<=target/c[len-1];i++){ sub(c,len-1,target-i*c[len-1],m1); vector
                          
                           
                            >& vec1=m1[pair
                            
                             (len-1,target-i*c[len-1])]; for(int j=0;j
                             

> combinationSum(vector

&candidates, int target) { // Start typing your C/C++ solution below // DO NOT write int main() function set

s; for(int i=0;i

iv(s.begin(),s.end()); map

,vector

> > m1; sub(candidates,candidates.size(),target,m1); vector

>& ret= m1[pair

(candidates.size(),target)]; set

> alp; for(int i=0;i