<p>You are given an alphanumeric string <code>s</code>. (<strong>Alphanumeric string</strong> is a string consisting of lowercase English letters and digits).</p>

<p>You have to find a permutation of the string where no letter is followed by another letter and no digit is followed by another digit. That is, no two adjacent characters have the same type.</p>

<p>Return <em>the reformatted string</em> or return <strong>an empty string</strong> if it is impossible to reformat the string.</p>

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

<pre>
<strong>Input:</strong> s = &quot;a0b1c2&quot;
<strong>Output:</strong> &quot;0a1b2c&quot;
<strong>Explanation:</strong> No two adjacent characters have the same type in &quot;0a1b2c&quot;. &quot;a0b1c2&quot;, &quot;0a1b2c&quot;, &quot;0c2a1b&quot; are also valid permutations.
</pre>

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

<pre>
<strong>Input:</strong> s = &quot;leetcode&quot;
<strong>Output:</strong> &quot;&quot;
<strong>Explanation:</strong> &quot;leetcode&quot; has only characters so we cannot separate them by digits.
</pre>

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

<pre>
<strong>Input:</strong> s = &quot;1229857369&quot;
<strong>Output:</strong> &quot;&quot;
<strong>Explanation:</strong> &quot;1229857369&quot; has only digits so we cannot separate them by characters.
</pre>

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

<ul>
	<li><code>1 &lt;= s.length &lt;= 500</code></li>
	<li><code>s</code> consists of only lowercase English letters and/or digits.</li>
</ul>

class Solution {
public:
    string reformat(string s) 
    {
        string digits;
        string letters;

        if( s.length() == 1 ) return s;

        for( int i = 0; i < s.length(); i++ )
        {
            if( isdigit( s[i]) ) digits += s[i];
            if( isalpha( s[i]) ) letters += s[i]; 
        }; 

        string prazan = "";

        if( digits.length() == 0 ) return prazan;
        if( letters.length() == 0 ) return prazan;
        if( abs( (int)(digits.length()) - (int)(letters.length())) > 1 ) 
            return prazan;



        int i = 0, j = 0;

        if( digits.length() > letters.length() )
        {
            while( i < digits.length() && j < letters.length() )
            {
                prazan += digits[i++];
                prazan += letters[j++];
            };
        }else
        {
             while( i < digits.length() && j < letters.length() )
            {
                prazan += letters[j++];
                prazan += digits[i++];

            }

        }

        while( j < letters.length() ) prazan += letters[j++];
        while( i < digits.length() ) prazan += digits[i++];

        return prazan;
    }
};
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