<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:
    void fun(int ind, int target, vector<int>& candidates,
             vector<vector<int>>& ans, vector<int> v) {

        if (target == 0) {
            ans.push_back(v);
            return;
        }
        if (target < 0)
            return;
        if (ind < 0)
            return;

        for (int i = ind - 1; i >= 0; i--) {
            if (i + 1 < candidates.size() &&
                candidates[i] != candidates[i + 1]) {
                fun(i, target, candidates, ans, v);
                break;
            }
        }

        v.push_back(candidates[ind]);
        fun(ind - 1, target - candidates[ind], candidates, ans, v);
        v.pop_back();
    }
    vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {
        sort(candidates.begin(), candidates.end());
        vector<vector<int>> ans;
        vector<int> v;
        fun(candidates.size() - 1, target, candidates, ans, v);

        return ans;
    }
};
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