Almost complete binary tree of height h

  • For h = 0, just a single node
  • For h = 1, left child or two children
  • For h ≥ 2, either:
    • the left subtree of the root is complete with height h-1 and the right is almost complete with height h-1, OR
    • the left is almost complete with height h-1 and the right is complete with height h-2