<p>You are given an array of strings <code>products</code> and a string <code>searchWord</code>.</p>

<p>Design a system that suggests at most three product names from <code>products</code> after each character of <code>searchWord</code> is typed. Suggested products should have common prefix with <code>searchWord</code>. If there are more than three products with a common prefix return the three lexicographically minimums products.</p>

<p>Return <em>a list of lists of the suggested products after each character of </em><code>searchWord</code><em> is typed</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> products = [&quot;mobile&quot;,&quot;mouse&quot;,&quot;moneypot&quot;,&quot;monitor&quot;,&quot;mousepad&quot;], searchWord = &quot;mouse&quot;
<strong>Output:</strong> [[&quot;mobile&quot;,&quot;moneypot&quot;,&quot;monitor&quot;],[&quot;mobile&quot;,&quot;moneypot&quot;,&quot;monitor&quot;],[&quot;mouse&quot;,&quot;mousepad&quot;],[&quot;mouse&quot;,&quot;mousepad&quot;],[&quot;mouse&quot;,&quot;mousepad&quot;]]
<strong>Explanation:</strong> products sorted lexicographically = [&quot;mobile&quot;,&quot;moneypot&quot;,&quot;monitor&quot;,&quot;mouse&quot;,&quot;mousepad&quot;].
After typing m and mo all products match and we show user [&quot;mobile&quot;,&quot;moneypot&quot;,&quot;monitor&quot;].
After typing mou, mous and mouse the system suggests [&quot;mouse&quot;,&quot;mousepad&quot;].
</pre>

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

<pre>
<strong>Input:</strong> products = [&quot;havana&quot;], searchWord = &quot;havana&quot;
<strong>Output:</strong> [[&quot;havana&quot;],[&quot;havana&quot;],[&quot;havana&quot;],[&quot;havana&quot;],[&quot;havana&quot;],[&quot;havana&quot;]]
<strong>Explanation:</strong> The only word &quot;havana&quot; will be always suggested while typing the search word.
</pre>

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

<ul>
	<li><code>1 &lt;= products.length &lt;= 1000</code></li>
	<li><code>1 &lt;= products[i].length &lt;= 3000</code></li>
	<li><code>1 &lt;= sum(products[i].length) &lt;= 2 * 10<sup>4</sup></code></li>
	<li>All the strings of <code>products</code> are <strong>unique</strong>.</li>
	<li><code>products[i]</code> consists of lowercase English letters.</li>
	<li><code>1 &lt;= searchWord.length &lt;= 1000</code></li>
	<li><code>searchWord</code> consists of lowercase English letters.</li>
</ul>

class Solution {
public:
    struct TreeNode {
        bool isWord;
        char letter;
        vector<TreeNode*> children;
    };

    TreeNode* getChildAt(char letter, TreeNode* node) {
        for (auto child : node->children) {
            if (child->letter == letter) {
                return child;
            }
        }
        return nullptr;
    }

    void addKey(TreeNode* node, string key) {
        TreeNode* current = node;
        for (int i = 0; i < key.size(); i++) {
            char letter = key[i];
            TreeNode* temp = getChildAt(letter, current);
            if (temp == nullptr) {
                temp = new TreeNode();
                temp->letter = letter;
                current->children.push_back(temp);
                sort(current->children.begin(), current->children.end(),
                 [](TreeNode* node1, TreeNode* node2) 
                { return node2->letter >= node1->letter; });
            }
            if (i == key.size() - 1) {
                temp->isWord = true;
            }
            current = temp;
        }
    }

    void getKeys(TreeNode* node, string prefix, vector<string>& result) {
        if (result.size() == 3) {
           return;
        }
        prefix += node->letter;
        if (node->isWord) {
            result.push_back(prefix);
        }
        
        if (node->children.size() > 0) {
            for (TreeNode* child : node->children) {
                getKeys(child, prefix, result);
            }
        }
    }

    vector<string> findKeys(TreeNode* node, string prefix) {
        vector<string> result;
        TreeNode* current = node;
        for (int i = 0; i < prefix.size(); i++) {
            char letter = prefix[i];
            TreeNode* temp = getChildAt(letter, current);
            if (!temp) {
                return result;
            }
            current = temp;
        }

        if (current->isWord) {
            result.push_back(prefix);
        }

        for (TreeNode* child : current->children) {
            getKeys(child, prefix, result);
        }

        vector<string> test;
        test.push_back(to_string(result.size()));
        return result;
    }

    vector<vector<string>> suggestedProducts(vector<string>& products, string searchWord) {
        TreeNode* root = new TreeNode();
        for (int i = 0; i < products.size(); i++) {
            addKey(root, products[i]);
        }

        vector<vector<string>> answer;
        for (int i = 1; i <= searchWord.size(); i++) {
            answer.push_back(findKeys(root, searchWord.substr(0, i)));
        }
        //answer.push_back(findKeys(root, searchWord));
        return answer;
    }
};
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