<p>Given two binary search trees <code>root1</code> and <code>root2</code>, return <em>a list containing all the integers from both trees sorted in <strong>ascending</strong> order</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2019/12/18/q2-e1.png" style="width: 457px; height: 207px;" />
<pre>
<strong>Input:</strong> root1 = [2,1,4], root2 = [1,0,3]
<strong>Output:</strong> [0,1,1,2,3,4]
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2019/12/18/q2-e5-.png" style="width: 352px; height: 197px;" />
<pre>
<strong>Input:</strong> root1 = [1,null,8], root2 = [8,1]
<strong>Output:</strong> [1,1,8,8]
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li>The number of nodes in each tree is in the range <code>[0, 5000]</code>.</li>
	<li><code>-10<sup>5</sup> &lt;= Node.val &lt;= 10<sup>5</sup></code></li>
</ul>


class Solution {
public:
    vector<int> getAllElements(TreeNode* root1, TreeNode* root2) {
        vector<int> list1, list2;
        inOrderTraversal(root1, list1);
        inOrderTraversal(root2, list2);
        
        // Merge the two sorted lists
        vector<int> result;
        mergeSortedLists(list1, list2, result);
        
        return result;
    }

private:
    void inOrderTraversal(TreeNode* root, vector<int>& list) {
        if (!root) return;
        inOrderTraversal(root->left, list);
        list.push_back(root->val);
        inOrderTraversal(root->right, list);
    }

    void mergeSortedLists(const vector<int>& list1, const vector<int>& list2, vector<int>& result) {
        result.resize(list1.size() + list2.size());
        merge(list1.begin(), list1.end(), list2.begin(), list2.end(), result.begin());
    }
};

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