<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 {
private:
   void solve(int index,vector<int> &cand,int n,int t,vector<int> temp,vector<vector<int>> &ans){
    //base case
        if(t==0){
            ans.push_back(temp);
            return;
        }

        if(index>=n)
           return;

        unordered_map<int,int> visited;   
        
        for(int i=index+1;i<n;i++){
            if(!visited[cand[i]] && t>=cand[i]){
                temp.push_back(cand[i]);
                visited[cand[i]] = true;
                solve(i,cand,n,t-cand[i],temp,ans);
                temp.pop_back();
            }
        }
   }
    
  
public:
    vector<vector<int>> combinationSum2(vector<int>& cand, int target) {
        vector<vector<int>> ans;
        int n = cand.size();
        sort(cand.begin(),cand.end());

        vector<int> temp;
        unordered_map<int,int> visited;

  
        for(int i=0;i<n;i++){
            if(!visited[cand[i]] && target>=cand[i]){
                visited[cand[i]] = true;
                temp.push_back(cand[i]);
                solve(i,cand,n,target-cand[i],temp,ans);
                temp.pop_back();
            }
        }

        return ans;
    }
};
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