<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 sol(vector<int>& candidates, int target, int i, vector<vector<int>>&ans, vector<int>curr ){
        
        if(target == 0){
           ans.push_back(curr);
           return;
        }

        if (i >= candidates.size()){
            return;
        }

        int j = i;
        while(j<candidates.size() && candidates[i] == candidates[j]){
            j++;
        }

        if(candidates[i] > target){
            return sol(candidates, target, j, ans, curr);
        }else{
            int k = i;
            while(k <= j){
                int c = k-i;
                int val = c*candidates[i];
                if(c){
                    // cout<<curr.size()<<" ";
                    curr.push_back(candidates[i]);
                }
                if(target - c*candidates[i] < 0){
                    break;
                }
                sol(candidates, target - c*candidates[i], j, ans, curr);
                k++;
            }
        }
    }

    vector<vector<int>> combinationSum2(vector<int>& candidates, int target) {
        sort(candidates.begin(), candidates.end());
        vector<vector<int>>ans;
        vector<int>curr;
        sol(candidates, target, 0, ans, curr);
        return ans;
    }
};
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