题目描述:
方法一:回溯
class Solution: def combinationSum3(self, k: int, n: int) -> List[List[int]]: res = [] def helper(k,n,start,tmp): if k==0: if n==0: res.append(tmp) return for i in range(start,10): if n - i < 0:break helper(k-1,n-i,i+1,tmp+[i]) helper(k,n,1,[]) return res