bc

/*
 *
 * Towers of Hanoi
 *
 * By: P.H. Hirst
 *
 * hanoi(n) will print the moves to solve the
 * Towers of Hanoi puzzle with n disks.
 *
 * hanoi(n,s,d,u) will print the moves to transfer
 * n disks from spire s to spire d using spire u
 * as an intermediate.
 *
 */

define hanoi(n,s,d,u) {
    auto i, os

    if (n <= 0) { return }

    if (s == 0) { s = 1 }
    if (d == 0) { d = 3 }
    if (u == 0) { u = 2 }

    hanoi(n-1, s, u, d)

    os = scale; scale = 0
    print "Move disk ", n, " from ", s, " to ", d, "\n"
    scale = os

    hanoi(n-1, u, d, s)
}