<p>In a warehouse, there is a row of barcodes, where the <code>i<sup>th</sup></code> barcode is <code>barcodes[i]</code>.</p>

<p>Rearrange the barcodes so that no two adjacent barcodes are equal. You may return any answer, and it is guaranteed an answer exists.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<pre><strong>Input:</strong> barcodes = [1,1,1,2,2,2]
<strong>Output:</strong> [2,1,2,1,2,1]
</pre><p><strong class="example">Example 2:</strong></p>
<pre><strong>Input:</strong> barcodes = [1,1,1,1,2,2,3,3]
<strong>Output:</strong> [1,3,1,3,1,2,1,2]
</pre>
<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= barcodes.length &lt;= 10000</code></li>
	<li><code>1 &lt;= barcodes[i] &lt;= 10000</code></li>
</ul>

class Solution {
public:
    vector<int> rearrangeBarcodes(vector<int>& barcodes) {
        unordered_map<int, int> freq;
        for (auto& x : barcodes)
            freq[x]++;
        
        vector<pair<int, int>> A(freq.begin(), freq.end());
        sort(A.begin(), A.end(), [](const pair<int, int>& a, const pair<int, int>& b) {
            return a.second > b.second;
        });
        int i = 0, n = barcodes.size();
        for (auto [code, cnt] : A) {
            while (cnt--) {
                barcodes[i] = code;
                i += 2;
                if (i >= n) {
                    i = 1;
                }
            }
        }
        return barcodes;
    }
};
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