The Heapsort Algorithm

• After array has been turned into a heap, repeatedly remove the root element
  • Swap root element with last element of the tree and then reduce the tree length
• Removed root ends up in the last position of the array, which is no longer needed by the heap
• We can use the same array both to hold the heap (which gets shorter with each step)
  and the sorted sequence (which gets longer with each step)
• Use a max-heap rather than a min-heap so that sorted sequence is accumulated in the correct order