<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 combinationSumHelper(vector<int>& candidates, int& target, vector<int> nums, set<vector<int>>& ans, int index) {
        int sum = accumulate(nums.begin(), nums.end(), 0);
        if(sum == target) {
            sort(nums.begin(), nums.end());
            ans.insert(nums);
            return;
        }
        for(int i = index; i < candidates.size(); i++) {
            if(sum + candidates[i] <= target) {
                int temp = candidates[i];
                nums.push_back(temp);
                candidates.erase(candidates.begin() + i);
                combinationSumHelper(candidates, target, nums, ans, index);
                candidates.insert(candidates.begin() + i, temp);
                nums.pop_back();
            }
            int sum2 = 0;
            while(i + 1 < candidates.size() && candidates[i] == candidates[i + 1] && candidates[i] == candidates[candidates.size() - 1] && sum + sum2 < target) {
                sum2 += candidates[i + 1];
                if(sum + sum2 == target) {
                    for(int j = 0; j < sum2 / candidates[i]; j++) {
                        nums.push_back(candidates[i]);
                    }
                    sort(nums.begin(), nums.end());
                    ans.insert(nums);
                    return;
                }
                i++;
            }
        }
        return;
    }

    vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {
        set<vector<int>> ans;
        vector<vector<int>> ansReturn;
        sort(candidates.begin(), candidates.end(), std::greater<>()); // Sort Reversed Order
        combinationSumHelper(candidates, target, {}, ans, 0);
        for(vector<int> v : ans) {
            ansReturn.push_back(v);
        }
        return ansReturn;

    }
};
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