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
class Solution {
Set<List<Integer>> res = new HashSet<>(); // !SET
public List<List<Integer>> combinationSum2(int[] candidates, int target) {
List<Integer> current = new ArrayList<>();
Arrays.sort(candidates); // !SET
search(candidates, 0, target, current);
return new ArrayList<>(res);
}
void search(int[] candidates, int start, int target, List<Integer> current) {
if (target == 0) {
res.add(new ArrayList<>(current)); // !SET we only add unique arrays lists, order is preserved because we had sorted candidates previously
return;
}
for (int i = start; i < candidates.length; i++) {
int remainder = target - candidates[i];
if (remainder < 0) continue;
current.add(candidates[i]);
search(candidates, i + 1, remainder, current);
Integer prev = current.remove(current.size() - 1);
}
}
}