[LeetCode] 0040. Combination Sum II

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Table of contents

Medium

Given a collection of candidate numbers (candidates) and a target number (target), find all unique combinations in candidates where the candidate numbers sum to target.

Each number in candidates may only be used once in the combination.

Note: The solution set must not contain duplicate combinations.

Example 1:

Input: candidates = [10,1,2,7,6,1,5], target = 8
Output: 
[
[1,1,6],
[1,2,5],
[1,7],
[2,6]
]

Example 2:

Input: candidates = [2,5,2,1,2], target = 5
Output: 
[
[1,2,2],
[5]
]

Constraints:

1 <= candidates.length <= 100
1 <= candidates[i] <= 50
1 <= target <= 30

Python

				
					# time complexity: O(2^n) # space complexity: O(n) from typing import List class Solution: def combinationSum2(self, candidates: List[int], target: int) -> List[List[int]] : answer = [] candidates.sort() self.backtrack(candidates, target, 0, [], answer) return answer def backtrack(self, candidates, target: int, totalIdx: int, path: List[int], answer : List[int]): if target < 0: return if target == 0: answer.append(path) return for i in range(totalIdx, len(candidates)): if i > totalIdx and candidates[i] == candidates[i - 1]: continue self.backtrack( candidates, target - candidates[i], i + 1, path + [candidates[i]], answer, ) candidates = [10, 1, 2, 7, 6, 1, 5] target = 8 print(Solution().combinationSum2(candidates, target))

Medium

Python

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