[Leet Code] Unique Number of Occurrences

Leetcode: https://leetcode.com/problems/unique-number-of-occurrences/

Problem:

Given an array of integers arr, write a function that returns true if and only if the number of occurrences of each value in the array is unique.

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

Solution:

class Solution(object):
    def uniqueOccurrences(self, arr):
        """
        :type arr: List[int]
        :rtype: bool
        """
        answers = []
        for i in set(arr):
            answers.append(arr.count(i))
        return len(answers) == len(set(answers))