1207\. Unique Number of Occurrences

Easy

Given an array of integers `arr`, return `true` if the number of occurrences of each value in the array is **unique**, or `false` otherwise.

**Example 1:**

**Input:** arr = [1,2,2,1,1,3]

**Output:** true

**Explanation:** The value 1 has 3 occurrences, 2 has 2 and 3 has 1. No two values have the same number of occurrences.

**Example 2:**

**Input:** arr = [1,2]

**Output:** false

**Example 3:**

**Input:** arr = [-3,0,1,-3,1,1,1,-3,10,0]

**Output:** true

**Constraints:**

*   `1 <= arr.length <= 1000`
*   `-1000 <= arr[i] <= 1000`