40. Combination Sum II

Problem Link

Description

---

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

Solution

---

Python3

class Solution:
    def combinationSum2(self, candidates: List[int], target: int) -> List[List[int]]:
        N = len(candidates)
        candidates.sort()
        res = []
 
        def go(index, curr, path):
            if curr == target:
                res.append(path[:])
                return
            
            if index == N: return
 
            for i in range(index, N):
                if i > index and candidates[i] == candidates[i - 1]: continue
 
                if candidates[i] + curr <= target:
                    path.append(candidates[i])
                    go(i + 1, candidates[i] + curr, path)
                    path.pop()
 
        go(0, 0, [])
        return res