Combination Sum leetcode java

题目：

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]

题解：

还是老问题，用DFS找解决方案，不同点是，这道题： The same repeated number may be chosen from C unlimited number of times.

所以，每次跳进递归不用都往后挪一个，还可以利用当前的元素尝试。

同时，这道题还要判断重复解。用我之前介绍的两个方法：

}  
     
          ArrayList<ArrayList<Integer>> res){  
                                            res.add(                      }
         
                                    item.add(candidates[i]);
                          helper(candidates,newtarget,i,item,res);            }  
     }