Combination sum II

Problem Given candidate numbers (which may contain duplicates) and a target, return all unique combinations summing to the target; each candidate may be used at most once.

Input / Output

• Input: int array candidates, int target.
• Output: a list of unique combinations that sum to target.

Constraints

• Up to 100 candidates, target <= 30 (classic bounds).
• The output must contain no duplicate combinations.
• Each candidate may be used at most once within a combination.

Example

• candidates = [10,1,2,7,6,1,5], target = 8 → [[1,1,6],[1,2,5],[1,7],[2,6]].