题目：

题解：

from typing import Listclass Solution:def combinationSum(self, candidates: List[int], target: int) -> List[List[int]]:def dfs(candidates, begin, size, path, res, target):if target < 0:returnif target == 0:res.append(path)returnfor index in range(begin, size):dfs(candidates, index, size, path + [candidates[index]], res, target - candidates[index])size = len(candidates)if size == 0:return []path = []res = []dfs(candidates, 0, size, path, res, target)return res