python
class Solution:
def combinationSum3(self, k: int, n: int) -> List[List[int]]:
ans = []
path = []
# Simplist
# choose or not
def dfs(i):
if len(path) == k:
if sum(path) == n: ans.append(path[:])
return
if i == 10:
return
# not choose
dfs(i+1)
# choose
path.append(i)
dfs(i+1)
path.pop()
dfs(1)
return ans