<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 {
    struct TrieNode {
        std::array<TrieNode*, 26> children;
        bool wordEnd{false};

        TrieNode* getNode(char ch) {
            return children[ch - 'a'];
        }

        void addWord(const std::string& word, int pos = 0){
            if(pos == word.size()) {
                wordEnd = true;
            } else {
                int idx = word[pos] - 'a';
                if(!children[idx]) {
                    children[idx] = new TrieNode();
                }
                children[idx]->addWord(word, pos + 1);
            }
        }
        bool getSmallestThree(const std::string& prefix, std::vector<std::string>& result) {
            if(result.size() == 3) {
                return true;
            }
            if(wordEnd) {
                result.emplace_back(prefix);
            }
            for(int i = 0; i < children.size(); ++i) {
                if(children[i] && children[i]->getSmallestThree(prefix + std::string(1, i + 'a'), result)) {
                    return true;
                }
            }
            return false;
        }
    };
public:
    vector<vector<string>> suggestedProducts(vector<string>& products, string searchWord) {
        TrieNode root;
        for(const auto& product : products) {
            root.addWord(product);
        }
        TrieNode* currentNode = &root;
        vector<vector<string>> ans;
        std::string prefix;
        for(char ch : searchWord) {
            prefix.append(1, ch);
            currentNode =  currentNode->getNode(ch);
            if(nullptr == currentNode) {
                break;
            }
            std::vector<std::string> smallestThree;
            currentNode->getSmallestThree("", smallestThree);
            for(int i = 0; i < smallestThree.size(); ++i) {
                smallestThree[i] = prefix + smallestThree[i];
            }
            ans.emplace_back(smallestThree);
        }
        ans.resize(searchWord.size());
        return ans;
    }
};
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