<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>

struct Node {
    unique_ptr<Node> child[26];
    bool isTerminal;
    Node() : isTerminal(false) {}
};

class Trie {
    unique_ptr<Node> root;

public:
    Trie() : root(make_unique<Node>()) {}

    void add(const string& word) {
        Node* temp = root.get();
        for (char c : word) {
            int index = c - 'a';
            if (!temp->child[index]) {
                temp->child[index] = make_unique<Node>();
            }
            temp = temp->child[index].get();
        }
        temp->isTerminal = true;
    }

    void search(const string& prefix, vector<vector<string>>& ans, int idx) {
        Node* temp = root.get();
        for (char c : prefix) {
            int index = c - 'a';
            if (!temp->child[index]) return;
            temp = temp->child[index].get();
        }
        collectSuggestions(temp, prefix, ans, idx);
    }

private:
    void collectSuggestions(Node* node, string prefix, vector<vector<string>>& ans, int idx) {
        if (ans[idx].size() >= 3) return;  // Stop collecting if we already have 3 suggestions
        if (node->isTerminal) {
            ans[idx].push_back(prefix);
        }
        for (int i = 0; i < 26; ++i) {
            if (node->child[i]) {
                collectSuggestions(node->child[i].get(), prefix + char(i + 'a'), ans, idx);
            }
        }
    }
};

class Solution {
public:
    vector<vector<string>> suggestedProducts(vector<string>& products, const string& searchWord) {
        Trie trie;
        vector<vector<string>> ans(searchWord.size());

        for (const string& product : products) {
            trie.add(product);
        }

        for (int i = 1; i <= searchWord.size(); ++i) {
            trie.search(searchWord.substr(0, i), ans, i - 1);
        }

        return ans;
    }
};
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