Towers of Hanoi

From: "John Bester" <jbester@ilink.nis.za>

The towers of hanoi is based on a very simple algorithm. I'll give you the algorithm and you can implement it.

type

THanoiBin = 0..2;

THanoiLevel = 0..9;

procedure MoveDisc(FromPin, ToPin : THanoiPin; Level : THanoiLevel);

// This one you have to implement yourself. It moves 1 disc from a pin to another.

// The disc to be moved must be on top (No discs above it)

You can represent the 3 towers in any way you want. 3 Stacks might probably the easiest. In this way MoveDisc will become MoveTopDisc and will move the disc on the top of the FromPin to ToPin and MoveTower will take a pointer to the base of a stack in stead of a level. Or you can simply use three arrays [THanoiLevel] of boolean in which case true means that the disc with the particular size depicted by THanoiLevel is on the tower.

procedure MoveTower(FromPin, ToPin : THanoiPin; Level : THanoiLevel);

begin

if HanoiLevel <= High(THanoiLevel) then

begin

MoveTower(FromPin, 3 - FromPin - ToPin, Level + 1);

MoveDisc(FromPin, ToPin, Level);

MoveTower(3 - FromPin - ToPin, ToPin, Level + 1);

end;

end;

To move the entire tower, you call MoveTower with the following as follows:

MoveTower(0, 1, Low(THanoiLevel));