<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;
    map<int,int> counter;
    void addcomb(map<int,int>::iterator it,vector<int> &res,int target){
        if(target == 0){
            ans.push_back(res);
            return;
        }
        if(it == counter.end() || target < 0)
            return;
        int val = it->first, count = it->second,i=0;
        it++;
        while(i*val <= target){
            addcomb(it,res,target-(i*val));
            res.push_back(val);
            if(i==count){
                res.pop_back();
                break;
            }
            i++;
        }
        while(i>0){
            res.pop_back();
            i--;
        }
    }
    vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {
       n=candidates.size();
       for(int i=0;i<n;i++)
       if(candidates[i] <= target){
            if(target/candidates[i] >= ( 1 + counter[candidates[i]]))
                counter[candidates[i]]++;
        }
        
        vector<int> res={};
        addcomb(counter.begin(),res,target);
        return ans;
    }
};
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