1207-unique-number-of-occurrences.rb

# frozen_string_literal: true

# 1207. Unique Number of Occurrences
# https://leetcode.com/problems/unique-number-of-occurrences
# Easy

=begin
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
=end

# @param {Integer[]} arr
# @return {Boolean}
def unique_occurrences(arr)
  !arr.tally.values.uniq!
end

# **************** #
#       TEST       #
# **************** #

require "test/unit"
class Test_unique_occurrences < Test::Unit::TestCase
  def test_
    assert_equal true, unique_occurrences([1, 2, 2, 1, 1, 3])
    assert_equal false, unique_occurrences([1, 2])
    assert_equal true, unique_occurrences([-3, 0, 1, -3, 1, 1, 1, -3, 10, 0])
  end
end