<p>Given a string <code>s</code> and an array of strings <code>words</code>, return <em>the number of</em> <code>words[i]</code> <em>that is a subsequence of</em> <code>s</code>.</p>

<p>A <strong>subsequence</strong> of a string is a new string generated from the original string with some characters (can be none) deleted without changing the relative order of the remaining characters.</p>

<ul>
	<li>For example, <code>&quot;ace&quot;</code> is a subsequence of <code>&quot;abcde&quot;</code>.</li>
</ul>

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

<pre>
<strong>Input:</strong> s = &quot;abcde&quot;, words = [&quot;a&quot;,&quot;bb&quot;,&quot;acd&quot;,&quot;ace&quot;]
<strong>Output:</strong> 3
<strong>Explanation:</strong> There are three strings in words that are a subsequence of s: &quot;a&quot;, &quot;acd&quot;, &quot;ace&quot;.
</pre>

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

<pre>
<strong>Input:</strong> s = &quot;dsahjpjauf&quot;, words = [&quot;ahjpjau&quot;,&quot;ja&quot;,&quot;ahbwzgqnuk&quot;,&quot;tnmlanowax&quot;]
<strong>Output:</strong> 2
</pre>

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

<ul>
	<li><code>1 &lt;= s.length &lt;= 5 * 10<sup>4</sup></code></li>
	<li><code>1 &lt;= words.length &lt;= 5000</code></li>
	<li><code>1 &lt;= words[i].length &lt;= 50</code></li>
	<li><code>s</code> and <code>words[i]</code> consist of only lowercase English letters.</li>
</ul>

struct TrieNode {
    unordered_map<char, TrieNode*> children;
    int wordCount;
    TrieNode() : wordCount(0) {}
};

class Solution {
public:
    int numMatchingSubseq(string s, vector<string>& words) {
        int count = 0;
        TrieNode *root = new TrieNode();
        
        // Build the Trie
        for (string word : words)
        {
            TrieNode *node = root;
            for (char ch : word)
            {
                if (!node->children[ch]) node->children[ch] = new TrieNode();
                node = node->children[ch];
            }
            node->wordCount++;
        }


        // Vector of queues to store pointers to Trie nodes waiting for each character
        unordered_map<char, queue<TrieNode*>> pointers;
        
        // Initialize the pointers with the first level of children nodes
        for (auto& [key, child] : root->children) pointers[key].push(child);

        // Traverse the string `s` and move through the Trie accordingly
        for (char ch : s) 
        {
            int sz = pointers[ch].size();
            while (sz--) 
            {
                auto node = pointers[ch].front(); pointers[ch].pop();
                count += node->wordCount;
                // Add the next level of children to the corresponding queues
                for (auto& [key, child] : node->children) 
                {
                    pointers[key].push(child);
                }
            }
        }
        
        return count;
    }
};


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