LeetCode： Sort Array by Increasing Frequency

Question

Given an array of integers nums, sort the array in increasing order based on the frequency of the values. If multiple values have the same frequency, sort them in decreasing order.

Return the sorted array.

Example 1:

Input: nums = [1,1,2,2,2,3]

Output: [3,1,1,2,2,2]

Explanation: '3' has a frequency of 1, '1' has a frequency of 2, and '2' has a frequency of 3.

Example 2:

Input: nums = [2,3,1,3,2]

Output: [1,3,3,2,2]

Explanation: '2' and '3' both have a frequency of 2, so they are sorted in decreasing order.

Solution

def frequency_sort(nums)
  result = []
  answer = []
  nums.uniq.each do |num|
    freq = nums.count(num)
    result << [num, freq]
  end
  sorted_result = result.sort_by{ |num, freq| [freq, -num] }
  sorted_result.each do |item|
    item[1].times{ answer << item[0] }
  end
  answer
end