data-structures/java/Stack/TOH.java

/** Towers of Hanoi */
public enum operation { MOVE, TOH }

class TOHobj {
    public operation op;
    public int num;
    public Pole start, goal, temp;

    /** Recursive call operation */
    TOHobj(operation o, int n, Pole s, Pole g, Pole t)
    { op = o; num = n; start = s; goal = g; temp = t; }

    /** MOVE operation */
    TOHobj(operation o, Pole s, Pole g)
    { op = o; start = s; goal = g; }
}

static void TOH(int n, Pole start, Pole goal, Pole temp) {
    // Make a stack just big enough
    Stack<TOHobj> S = new AStack<TOHobj>(2 * n + 1);
    S.push(new TOHobj(operation.TOH, n, start, goal, temp));
    while (S.length() > 0) {
	TOHobj it = S.pop(); // Get next task
	if (it.op == operation.MOVE) // Do a move
	    move(it.start, it.goal);
	else if (it.num > 0) { // Imitate TOH recursive solution (in reverse)
	    S.push(new TOHobj(operation.TOH, it.numm - 1, it.temp, it.goal, it.start));
	    S.push(new TOHobj(operation.MOVE, it.start, it.goal)); // A move to do
	    S.push(new TOHobj(operation.TOH, it.num - 1, it.start, it.temp, it.goal));
	}
    }
}