## 题目描述
## 思路
思路与“40. 组合总和III”类似，多一个判断`cnt`是否与给定`k`相等的剪枝过程。
## code
```python
class Solution(object):
def combinationSum3(self, k, n):
"""
:type k: int
:type n: int
:rtype: List[List[int]]
"""
res = []
candidates = [x for x in range(1, 10)]
def dfs(path, istart, t
