<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>

class Solution {
public:
    int numMatchingSubseq(string s, vector<string>& words) {
        vector<queue<pair<int, int>>> charQueues(26);

        // Populate the queues with the words and their starting character indices
        for (int i = 0; i < words.size(); ++i) {
            charQueues[words[i][0] - 'a'].emplace(i, 0);
        }

        int ans = 0; // Initialize the answer to count matching subsequences

        // Iterate over each character in the string s
        for (char& c : s) {
            // Reference to the queue corresponding to the current character
            auto& queue = charQueues[c - 'a'];

            // Process each pair in the queue
            for (int t = queue.size(); t > 0; --t) {
                auto [wordIndex, charIndex] = queue.front();
                queue.pop();

                // Increment the character index to check the next character of the word
                ++charIndex;

                // If all characters in the word have been found in s, increment the answer
                if (charIndex == words[wordIndex].size()) {
                    ++ans;
                } else {
                    // Otherwise, push the pair back to the corresponding queue for the next character
                    charQueues[words[wordIndex][charIndex] - 'a'].emplace(wordIndex, charIndex);
                }
            }
        }

        // Return the total number of matching subsequences found
        return ans;

    }
};
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