<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 {
    void helper(vector<int> &candidates, vector<int> res, set<vector<int>> &ans, int target, int ind){
        if(target == 0){
            ans.insert(res);
            return;
        }
        if(target < 0)return;
        if(ind >= candidates.size()){
            return;
        }

        for(int i = ind; i < candidates.size(); i++){
            if(i > ind and candidates[i] == candidates[i - 1])continue;
            res.push_back(candidates[i]);
            helper(candidates, res, ans, target - candidates[i], i + 1);
            // i--;
            res.pop_back();
        }


    }
public:
    vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {
        set<vector<int>> ans;
        vector<int> res;
        sort(candidates.begin(), candidates.end());
        ios_base::sync_with_stdio(false);
        cin.tie(NULL);
        helper(candidates, res, ans, target, 0);
        vector<vector<int>> result(ans.begin(), ans.end());
        return result;
    }
};
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