<p>Given the <code>root</code> of a binary tree, return <em>the lowest common ancestor of its deepest leaves</em>.</p>

<p>Recall that:</p>

<ul>
	<li>The node of a binary tree is a leaf if and only if it has no children</li>
	<li>The depth of the root of the tree is <code>0</code>. if the depth of a node is <code>d</code>, the depth of each of its children is <code>d + 1</code>.</li>
	<li>The lowest common ancestor of a set <code>S</code> of nodes, is the node <code>A</code> with the largest depth such that every node in <code>S</code> is in the subtree with root <code>A</code>.</li>
</ul>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://s3-lc-upload.s3.amazonaws.com/uploads/2018/07/01/sketch1.png" style="width: 600px; height: 510px;" />
<pre>
<strong>Input:</strong> root = [3,5,1,6,2,0,8,null,null,7,4]
<strong>Output:</strong> [2,7,4]
<strong>Explanation:</strong> We return the node with value 2, colored in yellow in the diagram.
The nodes coloured in blue are the deepest leaf-nodes of the tree.
Note that nodes 6, 0, and 8 are also leaf nodes, but the depth of them is 2, but the depth of nodes 7 and 4 is 3.</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> root = [1]
<strong>Output:</strong> [1]
<strong>Explanation:</strong> The root is the deepest node in the tree, and it&#39;s the lca of itself.
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> root = [0,1,3,null,2]
<strong>Output:</strong> [2]
<strong>Explanation:</strong> The deepest leaf node in the tree is 2, the lca of one node is itself.
</pre>

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

<ul>
	<li>The number of nodes in the tree will be in the range <code>[1, 1000]</code>.</li>
	<li><code>0 &lt;= Node.val &lt;= 1000</code></li>
	<li>The values of the nodes in the tree are <strong>unique</strong>.</li>
</ul>

<p>&nbsp;</p>
<p><strong>Note:</strong> This question is the same as 865: <a href="https://leetcode.com/problems/smallest-subtree-with-all-the-deepest-nodes/" target="_blank">https://leetcode.com/problems/smallest-subtree-with-all-the-deepest-nodes/</a></p>

/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
public:
    TreeNode* lcaDeepestLeaves(TreeNode* root) {
        int maxDepth = 0;
        std::vector<TreeNode*> deepestLeaves;
        findDeepestLeaves(root, 0, maxDepth, deepestLeaves);
        
        // After finding the deepest leaves, find their LCA
        return findLCA(root, deepestLeaves);
    }

private:
    void findDeepestLeaves(TreeNode* node, int depth, int& maxDepth, std::vector<TreeNode*>& deepestLeaves) {
        if (!node) return;

        if (depth > maxDepth) {
            maxDepth = depth;
            deepestLeaves = {node};  // Reset to current node
        } else if (depth == maxDepth) {
            deepestLeaves.push_back(node);  // Add current node
        }

        findDeepestLeaves(node->left, depth + 1, maxDepth, deepestLeaves);
        findDeepestLeaves(node->right, depth + 1, maxDepth, deepestLeaves);
    }

    TreeNode* findLCA(TreeNode* root, const std::vector<TreeNode*>& deepestLeaves) {
        if (!root || std::find(deepestLeaves.begin(), deepestLeaves.end(), root) != deepestLeaves.end()) {
            return root;
        }

        TreeNode* left = findLCA(root->left, deepestLeaves);
        TreeNode* right = findLCA(root->right, deepestLeaves);

        if (left && right) return root;  // If both left and right are found, this is the LCA
        return left ? left : right;  // Return the non-null child
    }
};
22000