<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>

#include <unordered_map>
#include <algorithm>
#include <string>
using namespace std;

class Solution {
public:
    int minNumberOfFrogs(string croakOfFrogs) {
        int n = croakOfFrogs.size();
        unordered_map<char, int> hash;
        hash['c'] = 0;
        hash['r'] = 1;
        hash['o'] = 2;
        hash['a'] = 3;
        hash['k'] = 4;
        unordered_map<int, int> st;
        int currfrogs = 0, maxfrogs = 0;
        int i = 0;
        int ans = 0;
        while (i < n) {
            if (hash[croakOfFrogs[i]] == 0 || st[hash[croakOfFrogs[i]] - 1] > 0) {
                if(hash[croakOfFrogs[i]] == 0 )
                {
                    currfrogs++;
                    maxfrogs = max(currfrogs,maxfrogs);
                }
                if (hash[croakOfFrogs[i]] > 0) {
                    st[hash[croakOfFrogs[i]] - 1]--;
                    if (st[hash[croakOfFrogs[i]] - 1] == 0) {
                        st.erase(hash[croakOfFrogs[i]] - 1);
                    }
                }
                st[hash[croakOfFrogs[i]]]++;
                if (hash[croakOfFrogs[i]] == 4) {
                    currfrogs--;
                    st[hash[croakOfFrogs[i]]]--;
                    if (st[hash[croakOfFrogs[i]]] == 0) {
                        st.erase(hash[croakOfFrogs[i]]);
                    }
                }
            } else {
                return -1;
            }
            ans = max(ans, int(st.size()));
            i++;
        }
        
        // Check if all parts of "croak" are balanced
        if (st[0] != 0 || st[1] != 0 || st[2] != 0 || st[3] != 0 || st[4] != 0) {
            return -1;
        }

        return maxfrogs;
    }
};

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