<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>

class Solution {
public:
    int minNumberOfFrogs(string croakOfFrogs) {
        unordered_map<char, int> _map;
        _map['c'] = 1;
        _map['r'] = 2;
        _map['o'] = 3;
        _map['a'] = 4;
        _map['k'] = 5;

        int answer = 0;
        int cut = 0;
        vector<int> freq(5, 0);
        for (auto ch : croakOfFrogs) {
            bool check = true;
            if (_map[ch] == 0)
                return -1;
            for (int i = 0; i < _map[ch] - 1; i++) {
                if (freq[i] <= freq[_map[ch] - 1]) {
                    check = false;
                    break;
                }
            }

            if (check) {
                freq[_map[ch] - 1]++;
                int maxi = 0;
                if (ch == 'k') {
                    for (int i = 0; i <= 4; i++) {
                        maxi = max(maxi, freq[i]);
                        freq[i]--;
                    }
                    cut += 5;
                    answer = max(answer, maxi);
                }
            }
        }

        for (auto it : freq) {
            if (it != 0)
                return -1;
        }
        
        if (cut != croakOfFrogs.length())
            return -1;
        
        return answer;
    }
};
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