<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) {
        int l = s.length();
        queue<char> q1, q2;

        for(int i=0; i<l; i++) {
            char ch = s[i];
            if(ch >= '0' && ch <= '9') q1.push(ch);
            else q2.push(ch);
        }

        int l1 = q1.size();
        int l2 = q2.size();

        if(abs(l2 - l1) > 1) return "";

        if(l2 < l1) {
            auto tmp = q1;
            q1 = q2;
            q2 = tmp;
        }

        string res = "";

        while(!q1.empty() && !q2.empty()) {
            char c1 = q1.front();
            q1.pop();

            char c2 = q2.front();
            q2.pop();

            res+= c2;
            res+= c1;
        }

        while(!q1.empty()) {
            char c1 = q1.front();
            q1.pop();

            res+= c1;
        }

        while(!q2.empty()) {
            char c2 = q2.front();
            q2.pop();

            res+= c2;
        }

        return res;
    }
};
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