Minimum Number of Frogs Croaking
<p>You are given the string <code>croakOfFrogs</code>, which represents a combination of the string <code>&quot;croak&quot;</code> from different frogs, that is, multiple frogs can croak at the same time, so multiple <code>&quot;croak&quot;</code> are mixed.</p>

<p><em>Return the minimum number of </em>different<em> frogs to finish all the croaks in the given string.</em></p>

<p>A valid <code>&quot;croak&quot;</code> means a frog is printing five letters <code>&#39;c&#39;</code>, <code>&#39;r&#39;</code>, <code>&#39;o&#39;</code>, <code>&#39;a&#39;</code>, and <code>&#39;k&#39;</code> <strong>sequentially</strong>. The frogs have to print all five letters to finish a croak. If the given string is not a combination of a valid <code>&quot;croak&quot;</code> return <code>-1</code>.</p>

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

<pre>
<strong>Input:</strong> croakOfFrogs = &quot;croakcroak&quot;
<strong>Output:</strong> 1 
<strong>Explanation:</strong> One frog yelling &quot;croak<strong>&quot;</strong> twice.
</pre>

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

<pre>
<strong>Input:</strong> croakOfFrogs = &quot;crcoakroak&quot;
<strong>Output:</strong> 2 
<strong>Explanation:</strong> The minimum number of frogs is two. 
The first frog could yell &quot;<strong>cr</strong>c<strong>oak</strong>roak&quot;.
The second frog could yell later &quot;cr<strong>c</strong>oak<strong>roak</strong>&quot;.
</pre>

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

<pre>
<strong>Input:</strong> croakOfFrogs = &quot;croakcrook&quot;
<strong>Output:</strong> -1
<strong>Explanation:</strong> The given string is an invalid combination of &quot;croak<strong>&quot;</strong> from different frogs.
</pre>

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

<ul>
	<li><code>1 &lt;= croakOfFrogs.length &lt;= 10<sup>5</sup></code></li>
	<li><code>croakOfFrogs</code> is either <code>&#39;c&#39;</code>, <code>&#39;r&#39;</code>, <code>&#39;o&#39;</code>, <code>&#39;a&#39;</code>, or <code>&#39;k&#39;</code>.</li>
</ul>
String; Counting
class Solution:
    def minNumberOfFrogs(self, croakOfFrogs: str) -> int:
        if len(croakOfFrogs) % 5 != 0:
            return -1
        idx = {c: i for i, c in enumerate('croak')}
        cnt = [0] * 5
        ans = x = 0
        for i in map(idx.get, croakOfFrogs):
            cnt[i] += 1
            if i == 0:
                x += 1
                ans = max(ans, x)
            else:
                if cnt[i - 1] == 0:
                    return -1
                cnt[i - 1] -= 1
                if i == 4:
                    x -= 1
        return -1 if x else ans
