class Solution {
private:
vector<vector<int>> res;
vector<int> path;
void backtracking(vector<int>& candidates, int sum, int startIndex) {
// if (sum < 0) return;
if (sum == 0) {
res.push_back(path);
return;
}
for (int i = startIndex; i < candidates.size() && sum - candidates[i] >= 0; i++) {
if (i != startIndex && candidates[i] == candidates[i - 1]) continue;
path.push_back(candidates[i]);
backtracking(candidates, sum - candidates[i], i + 1);
path.pop_back();
}
}
public:
vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {
sort(candidates.begin(), candidates.end());
backtracking(candidates, target, 0);
return res;
}
};