<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 <int> cand;
    map< vector<int>, int > mp2;
    
    map<int, int> m;
    vector<vector<int>> ans;

    void recursion(int target, vector<int> &v, int index) {

        if (target < 0) {
            return;
        }

        for (int i = index; i < cand.size(); i++) {
            int x = cand[i];
            
            if (i > index && cand[i] == cand[i-1]) {
                continue;
            }

            if (target - x == 0 && m[x] > 0) {
                v.push_back(x);
                if (mp2.find(v) == mp2.end()) {
                    ans.push_back(v);
                    mp2[v] = 0;
                }

                v.pop_back();
            } else {

                if (m[x] <= 0 || target-x < 0)
                    continue;

                m[x]--;
                v.push_back(x);
                recursion(target-x, v, i+1);
                v.pop_back();
                m[x]++;
            }
        }


    }

    vector<vector<int>> combinationSum2(vector<int>& cand, int target) {

        // dp.resise(target, -1);
        sort(cand.begin(), cand.end());
        this->cand = cand;

        for (auto &x: cand) {
            m[x]++;
        }

        vector<int> v;
        
        recursion(target, v, 0);
        
        return ans;
    }
};
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