<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>


#define endl '\n'
#define pint pair<int, int>
#define vint vector<int>
#define vll vector<long long>
#define vpint vector<pair<int, int>>
#define vstr vector<string>
#define uset unordered_set
#define umap unordered_map
#define vbool vector<bool>
#define vvint vector<vector<int>>
#define vvvint vector<vector<vector<int>>>
#define ll long long
#define MOD 1000000007

class Solution {
public:
    void helper(vint &candidates, int target, int pos, vint &temp, vvint &ans) {
        int n = candidates.size();

        if(target == 0) {
            ans.push_back(temp);
            //temp.pop_back();
            return;
        }

        if(pos >= n || target < 0)
            return;

        int idx = pos;
        while(idx + 1 < n && candidates[idx] == candidates[idx + 1])
            idx++;

        helper(candidates, target, idx + 1, temp, ans);

        temp.push_back(candidates[pos]);
        helper(candidates, target - candidates[pos], pos + 1, temp, ans);
        temp.pop_back();

        return;
    }

    vvint combinationSum2(vint& candidates, int target) {
        int n = candidates.size();

        sort(candidates.begin(), candidates.end());

        vvint ans;

        vint temp;

        helper(candidates, target, 0, temp, ans);

        return ans;
    }
};
15365