<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>

void recursion(set<vector<int>>&sans,vector<int>&temp,vector<int>& f,int sum,int ind, int &target){
    if(sum==target){
        sans.insert(temp);
        return;
    }
    if(ind>30 || sum>target)return;
    
    vector<int>temp2=temp;

    for(int i=0;i<=f[ind];i++,temp.push_back(ind)){
        recursion(sans,temp,f,sum + (ind*i),ind+1,target);
    }
    
    temp=temp2;
}
class Solution {
public:
    vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {
        vector<int>f(31,0);
        for(auto it:candidates)if(it<=30)f[it]++;
        vector<vector<int>>ans;
        set<vector<int>>sans;
        vector<int>temp;
        int sum=0,ind=1;
        recursion(sans,temp,f,sum,ind,target);
        for(auto vec:sans){
            ans.push_back(vec);
        }
        return ans;
    }
};
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