Count the Number of Consistent Strings
<p>You are given a string <code>allowed</code> consisting of <strong>distinct</strong> characters and an array of strings <code>words</code>. A string is <strong>consistent </strong>if all characters in the string appear in the string <code>allowed</code>.</p>

<p>Return<em> the number of <strong>consistent</strong> strings in the array </em><code>words</code>.</p>

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

<pre>
<strong>Input:</strong> allowed = &quot;ab&quot;, words = [&quot;ad&quot;,&quot;bd&quot;,&quot;aaab&quot;,&quot;baa&quot;,&quot;badab&quot;]
<strong>Output:</strong> 2
<strong>Explanation:</strong> Strings &quot;aaab&quot; and &quot;baa&quot; are consistent since they only contain characters &#39;a&#39; and &#39;b&#39;.
</pre>

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

<pre>
<strong>Input:</strong> allowed = &quot;abc&quot;, words = [&quot;a&quot;,&quot;b&quot;,&quot;c&quot;,&quot;ab&quot;,&quot;ac&quot;,&quot;bc&quot;,&quot;abc&quot;]
<strong>Output:</strong> 7
<strong>Explanation:</strong> All strings are consistent.
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> allowed = &quot;cad&quot;, words = [&quot;cc&quot;,&quot;acd&quot;,&quot;b&quot;,&quot;ba&quot;,&quot;bac&quot;,&quot;bad&quot;,&quot;ac&quot;,&quot;d&quot;]
<strong>Output:</strong> 4
<strong>Explanation:</strong> Strings &quot;cc&quot;, &quot;acd&quot;, &quot;ac&quot;, and &quot;d&quot; are consistent.
</pre>

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

<ul>
	<li><code>1 &lt;= words.length &lt;= 10<sup>4</sup></code></li>
	<li><code>1 &lt;= allowed.length &lt;=<sup> </sup>26</code></li>
	<li><code>1 &lt;= words[i].length &lt;= 10</code></li>
	<li>The characters in <code>allowed</code> are <strong>distinct</strong>.</li>
	<li><code>words[i]</code> and <code>allowed</code> contain only lowercase English letters.</li>
</ul>
Bit Manipulation; Array; Hash Table; String; Counting
function countConsistentStrings(allowed: string, words: string[]): number {
    const set = new Set([...allowed]);
    const n = words.length;
    let ans = n;
    for (const word of words) {
        for (const c of word) {
            if (!set.has(c)) {
                ans--;
                break;
            }
        }
    }
    return ans;
}
