The standard sequential representation of binary trees is discussed. Then heapsort is discussed conceptually and specified in terms of pseudocode. A programming assignment is issued to write a Java program based on the pseudocode.

Pseudocode

pseudocode heapsort(a[],n)
   // create initial heap
   for i = floor(n/2) to 1 by -1 do
      adjust(i,n)
   end
   // sort
   for i = n-1 to 1 by -1 do
      t = a[i+1] 
      a[i+1] = a[1]
      a[1] = t
      adjust(1,i)
   end
end

pseudocode adjust(i,n)
   a = a[i]
   j = 2*i
   while ( j <= n ) do
      if ( j < n ) then
         if ( a[j] < a[j+1] ) then
            j = j + 1
         end
      end
      if ( a > a[j] ) then
         exit the loop
      end
      a[j/2] = a[j] 
      j = j*2
   end
   a[j/2] = a
end

Write an application program which generates 30 two digit integers, stores them in an array, and sorts the array by means of the heapsort algorithm. Arrange to display the elements of the array on one line (separating them by a space):

1. In the initial order.
2. Just after the initial heaps is created.
3. Just after each "pass" of the sort.

Proceed in the following way, working within a new Sorting project:

1. Establish the Heapsort program in the heapsort package.
2. Compile it and run it!