<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>

// To find lexicographically smallest, do dfs for each character from 'a' till 'z'

struct TrieNode {
    unordered_map<int, TrieNode*> links;
    bool isEnd;

    TrieNode() {
        isEnd = 0;
    }

    bool containsKey(char ch) {
        return links[ch - 'a'];
    }

    void putKey(TrieNode* node, char ch) {
        links[ch - 'a'] = node;
    }

    TrieNode* next(char ch) {
        return links[ch - 'a'];
    }
};

class Trie {
public:
    TrieNode* root;

    Trie() {
        root = new TrieNode();
    }

    void insert(string& word) {
        TrieNode* node = root;
        int level = 0;
        for(auto& ch : word) {
            if(!node->containsKey(ch)) {
                node->putKey(new TrieNode(), ch);
            }
            node = node->next(ch);
        }
        node->isEnd = 1;
    }

    vector<string> search(string& pre) {
        vector<string> res;
        TrieNode* node = root;
        for(auto& ch : pre) {
            if(!node->containsKey(ch)) {
                return {};
            }
            node = node->next(ch);
        }
        dfs(node, pre, res);
        return res;
    }

    void dfs(TrieNode* node, string pre, vector<string>& res) {
        if(node->isEnd) {
            if(res.size() < 3) {
                res.push_back(pre);
            }
        }
        if(res.size() == 3) {
            return;
        }

        for(char ch = 'a'; ch <= 'z'; ch++) {
            if(node->containsKey(ch)) {
                dfs(node->next(ch), pre + ch, res);
            }
        }
    }
};

class Solution {
public:
    vector<vector<string>> suggestedProducts(vector<string>& products, string searchWord) {
        vector<vector<string>> res;
        Trie trie;
        for(auto& product : products) {
            trie.insert(product);
        }
        string pre;
        for(auto& ch : searchWord) {
            pre += ch;
            vector<string> cur = trie.search(pre);
            res.push_back(cur);
        }
        return res;
    }
};
598630