문제

리트코드 39. Combunation Sum
난이도: ⭐⭐

Given an array of distinct integers candidates and a target integer target, return a list of all unique combinations of candidates where the chosen numbers sum to target. You may return the combinations in any order.

The same number may be chosen from candidates an unlimited number of times. Two combinations are unique if the frequency of at least one of the chosen numbers is different.
(숫자 집합 candidates를 조합해 합이 target이 되는 원소를 나열하라. 각 원소는 중복으로 나열 가능하다.)

예시 1

Input: candidates = [2,3,6,7], target = 7
Output: [[2,2,3],[7]]

예시 2

Input: candidates = [2], target = 1
Output: []

풀이 1: DFS로 중복 조합 그래프 탐색

class Solution:
    def combinationSum(self, candidates: List[int], target: int) -> List[List[int]]:
        result = []
        
        def dfs(csum, index, path):
            if csum < 0:
                return
            if csum == 0:
                result.append(path)
                return
            
            for i in range(index, len(candidates)):
                dfs(csum - candidates[i], i, path+[candidates[i]])
        
        dfs(target, 0, [])
        
        return result