<p>Given an array of integers <code>arr</code>, return <code>true</code> <em>if the number of occurrences of each value in the array is <strong>unique</strong> or </em><code>false</code><em> otherwise</em>.</p>

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

<pre>
<strong>Input:</strong> arr = [1,2,2,1,1,3]
<strong>Output:</strong> true
<strong>Explanation:</strong>&nbsp;The value 1 has 3 occurrences, 2 has 2 and 3 has 1. No two values have the same number of occurrences.</pre>

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

<pre>
<strong>Input:</strong> arr = [1,2]
<strong>Output:</strong> false
</pre>

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

<pre>
<strong>Input:</strong> arr = [-3,0,1,-3,1,1,1,-3,10,0]
<strong>Output:</strong> true
</pre>

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

<ul>
	<li><code>1 &lt;= arr.length &lt;= 1000</code></li>
	<li><code>-1000 &lt;= arr[i] &lt;= 1000</code></li>
</ul>

class Solution {
public:
    bool uniqueOccurrences(vector<int>& arr) {
        vector<int> occurrences;
        sort(arr.begin(), arr.end());
        int count = 1;
        for (int i = 0; i < arr.size() - 1; i++)
        {
            if (arr[i] == arr[i + 1])
            count++;
            else
            {
                occurrences.push_back(count);
                count = 1;
            }
        }
        occurrences.push_back(count);
        sort(occurrences.begin(), occurrences.end());
        for (int i = 0; i < occurrences.size()-1; i++){
            if (occurrences[i] == occurrences[i+1])
            {
                return false;
            }
        }
        return true;
    }
};
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