<p>Given a collection of candidate numbers (<code>candidates</code>) and a target number (<code>target</code>), find all unique combinations in <code>candidates</code>&nbsp;where the candidate numbers sum to <code>target</code>.</p>

<p>Each number in <code>candidates</code>&nbsp;may only be used <strong>once</strong> in the combination.</p>

<p><strong>Note:</strong>&nbsp;The solution set must not contain duplicate combinations.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> candidates = [10,1,2,7,6,1,5], target = 8
<strong>Output:</strong> 
[
[1,1,6],
[1,2,5],
[1,7],
[2,6]
]
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> candidates = [2,5,2,1,2], target = 5
<strong>Output:</strong> 
[
[1,2,2],
[5]
]
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;=&nbsp;candidates.length &lt;= 100</code></li>
	<li><code>1 &lt;=&nbsp;candidates[i] &lt;= 50</code></li>
	<li><code>1 &lt;= target &lt;= 30</code></li>
</ul>

class Solution {
public:
    vector<vector<int>> ans;
    int n;
    void addcomb(int pos,vector<int> &res,vector<int>& candidates,int target){
        if(target == 0){
            ans.push_back(res);
            return;
        }
        if(pos == n)
            return;
        int j,count=0,val;
        val=candidates[pos];
        while(pos<n && candidates[pos] == val){
            count++;
            pos++;
        }
        addcomb(pos,res,candidates,target);
        for(j=0;j<count;j++){
            target -=val;
            if(target<0)
                break;
            res.push_back(val);
            addcomb(pos,res,candidates,target);
        }
        while(j>0){
            res.pop_back();
            j--;
        }
    }
    vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {
       sort(candidates.begin(),candidates.end());
       n=candidates.size();
       for(int i=0;i<n;i++)
            if(candidates[i] > target){
                n=i;
                break;
            }
        vector<int> res={};
        addcomb(0,res,candidates,target);
        return ans;
    }
};
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