0040-combination-sum-ii.py

# 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))