# 40. Combination Sum II 组合之和之二

Given a collection of candidate numbers (candidates) and a target number (target), find all unique combinations in candidates where the candidate numbers sums to target.

Each number in candidates may only be used once in the combination.

Note:

All numbers (including target) will be positive integers. The solution set must not contain duplicate combinations.

Example 1:

Input: candidates = [10,1,2,7,6,1,5], target = 8,

``````A solution set is:
[
[1, 7],
[1, 2, 5],
[2, 6],
[1, 1, 6]
]
``````

Example 2:

Input: candidates = [2,5,2,1,2], target = 5,

``````A solution set is:
[
[1,2,2],
[5]
]
``````

Difficulty: Medium

``````class Solution {
public:
vector<vector<int>> combinationSum2(vector<int>& candidates, int target){
vector<vector<int>> res;
vector<int> solution;
sort(candidates.begin(), candidates.end());
findSum2(candidates,0,target,solution,res);
return res;
}

void findSum2(vector<int>& candidates,int start,int target,vector<int>& solution,vector<vector<int>>& res){
if (target < 0) return;
else if (target==0){
res.push_back(solution);
}else{
for (int i = start;i < candidates.size();i++){
if (i > start && candidates[i-1]==candidates[i]) continue;
solution.push_back(candidates[i]);
findSum2(candidates, i+1, target-candidates[i], solution, res);
solution.pop_back();
}
}
}
};
``````

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