<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 util(vector<vector<int>>& ans,
                vector<int> temp,
                vector<int>& ct, 
                int target, 
                int cursum, 
                int curind)
    {
        if(cursum > target)
            return;
        if(cursum == target)
        {
            ans.push_back(temp);
            return;
        }

        if(curind < 0)
            return;
        
        util(ans, temp, ct, target, cursum, curind-1);

        for(int i=0; i<ct[curind]; i++)
        {
            temp.push_back(curind);
            cursum += curind;
            util(ans, temp, ct, target, cursum, curind-1);
        }
    }

    vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {
        vector<vector<int>> ans;
        int n = candidates.size();
        vector<int> ct(51, 0);

        for(auto it : candidates)
            ct[it]++;

        vector<int> temp;
        util(ans, temp, ct, target, 0, 50);

        return ans;
    }
};
21915