LeetCode-in-All

215. Kth Largest Element in an Array

Medium

Given an integer array nums and an integer k, return the kth largest element in the array.

Note that it is the kth largest element in the sorted order, not the kth distinct element.

You must solve it in O(n) time complexity.

Example 1:

Input: nums = [3,2,1,5,6,4], k = 2

Output: 5

Example 2:

Input: nums = [3,2,3,1,2,4,5,5,6], k = 4

Output: 4

Constraints:

Solution

defmodule Solution do
  @spec find_kth_largest(nums :: [integer], k :: integer) :: integer
  def find_kth_largest(nums, k) do
  nums
    |> Enum.with_index()
    |> Enum.reduce(:gb_sets.new(), fn {n, i}, q ->
          cond do
            :gb_sets.is_member({n,i}, q) ->
              q
            :gb_sets.size(q) < k ->
              :gb_sets.insert({n,i}, q)
            true ->
              {smol, qq} = :gb_sets.take_smallest(q)
              :gb_sets.insert(max(smol, {n,i}), qq)
          end
        end)
    |> :gb_sets.smallest()
    |> elem(0)
  end
end