<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<vector<int>> indexes(s.length()+1,vector<int>(26,-1));
        for(int j=s.length()-1;j>=0;j--){
            indexes[j]=indexes[j+1];
            indexes[j][s[j]-'a']=j;
        }

        // for(int i=0;i<indexes.size();i++){
        //     cout<<i<<endl;
        //     for(int j=0;j<26;j++){
        //         if(indexes[i][j]!=-1){
        //             cout<<(char)(j+'a')<<" -> "<<indexes[i][j]<<endl;
        //         }
        //     }
        //     cout<<endl;
        // }

        int count=0;
        for(int i=0;i<words.size();i++){
            int flag=0;
            int driver=0;
            for(int j=0;j<words[i].size();j++){
                if(indexes[driver][words[i][j]-'a']!=-1){
                    driver=indexes[driver][words[i][j]-'a']+1;
                } else {
                    flag=1;
                    break;
                }
            }
            if(flag==0){
                count++;
            }
        }
        return count;
    }
};
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