Very simple heap implementation in ruby

minheap.rb

class MinHeap
  attr_reader :heap

  def initialize()
    @heap = []
  end
  
  def insert(element)
    @heap.push(element)
    heapify_up(@heap.size - 1)
  end
  
  def extract_min
    element = @heap[0]
    @heap[0] = @heap.pop
    heapify_down(0)
    element
  end
  
  private

  def heapify_up(num)
    return if num <= 0
    parent = (num - 1) / 2
    if @heap[num] < @heap[parent]
      temp = @heap[num]
      @heap[num] = @heap[parent]
      @heap[parent] = temp
    end
    heapify_up(parent)
  end
  
  def heapify_down(num)
    return if num > (@heap.size - 1)

    left_child = num * 2 + 1
    right_child = num * 2 + 2

    return if left_child > (@heap.size - 1)

    if right_child > (@heap.size - 1) 
      if @heap[num] > @heap[left_child]
        @heap[num], @heap[left_child] = @heap[left_child], @heap[num]
      end
      return
    end

    
    return if @heap[num] <= @heap[left_child] && @heap[num] <= @heap[right_child]
    
    if @heap[num] > @heap[right_child] && @heap[right_child] <= @heap[left_child]
      @heap[num], @heap[right_child] = @heap[right_child], @heap[num]
      heapify_down(right_child)
    elsif @heap[num] > @heap[left_child] && @heap[left_child] <= @heap[right_child]
      @heap[num], @heap[left_child] = @heap[left_child], @heap[num]
      heapify_down(left_child)
    end
  end
end