<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;
    void solve(int idx, int target, vector<bool> vis, vector<int>& candidates){
        if(target < 0) return;
        if(!target){
            vector<int>cur;
            for(int i = 0; i < vis.size(); i++){
                if(vis[i]) cur.push_back(candidates[i]);
            }
            ans.push_back(cur);
            return;
        }
        for(int i = idx; i < candidates.size(); i++){
            if (i == idx || candidates[i] != candidates[i - 1]) {
                vis[i] = 1;
                solve(i + 1, target - candidates[i], vis, candidates);
                vis[i] = 0;
            }
        }
    }
    vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {
        sort(candidates.begin(), candidates.end());
        solve(0, target, vector<bool>(candidates.size(), 0), candidates);
        return ans;
    }
};
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