```#!/usr/local/bin/ruby

NUM_ITEMS=20

def siftdown(numbers, root, bottom)
done = 0
while ((root*2 <= bottom) && (done == 0)) do
puts "entere while do loop\n"
if root*2 == bottom
maxChild = root * 2
elsif numbers[root*2] > numbers[root*2+1]
maxChild = root * 2
else
maxChild = root * 2 + 1
end
printf("top of if root = %d  maxChild = %d\n",root, maxChild)
if numbers[root] < numbers[maxChild]
puts "before swap"
printf("numbers[root=%d]=%d, numbers[maxChild=%d]=%d\n",root,numbers[root],maxChild,numbers[maxChild])
puts "swapping root and maxChild\n"
temp = numbers[root]
numbers[root] = numbers[maxChild]
numbers[maxChild] = temp
puts "after swap"
printf("numbers[root=%d]=%d, numbers[maxChild=%d]=%d\n",root,numbers[root],maxChild,numbers[maxChild])
root = maxChild
printf("bottom if root = %d = maxChild = %d\n",root,maxChild)
else
done = 1   # yes done
end
for i in 1..NUM_ITEMS do
printf("numbers[%d] = %d \n",i,numbers[i])
end
end
end

def heapSort(numbers)
bottom = NUM_ITEMS
for i in 1..bottom do
printf("numbers[%d]=%d \n",i,numbers[i])
end
puts "entering count down"
#  i = bottom/2 - 1
i = bottom/2
loop do
#   printf("%d \n", numbers[i])
siftdown(numbers, i, bottom)
i -= 1
break if i < 1
end
puts"done making heap, begin sort\n"
i = NUM_ITEMS
loop do
temp = numbers[1]
numbers[1] = numbers[i]
numbers[i] = temp
i -= 1
break if i < 1
siftdown(numbers, 1, i)
end
end

numbers = Array.new
srand(13)
for i in 1..NUM_ITEMS do
numbers[i] = rand(1000)
end

heapSort(numbers)
puts "Sorted numbers\n"
for i in 1..NUM_ITEMS do
printf("numbers[%d]=%d \n",i,numbers[i])
end```
Published in: Ruby