#
# The Towers Of Hanoi
# dc (Unix Desk Calculator) version
# Copyright (C) 2003 Amit Singh. All Rights Reserved.
# http://hanoi.kernelthread.com
#
# Tested under GNU dc 1.3
#

# Usage: dc -e n hanoi.dc
#        where n is the number of disks

[ # move(from, to)
    n           # print from
    [ --> ]n    # print " --> "
    p           # print to\n
    sw          # p doesn't pop, so get rid of the value
]sm

[ # init(n)
    sw          # tuck n away temporarily
    9           # sentinel as bottom of stack
    lw          # bring n back
    1           # "from" tower's label
    3           # "to" tower's label
    0           # processed marker
]si

[ # Move()
    lt          # push to
    lf          # push from
    lmx         # call move(from, to)
]sM

[ # code block <d>
    ln          # push n
    lf          # push from
    lt          # push to
    1           # push processed marker 1
    ln          # push n
    1           # push 1
    -           # n - 1
    lf          # push from
    ll          # push left
    0           # push processed marker 0
]sd

[ # code block <e>
    ln          # push n
    1           # push 1
    -           # n - 1
    ll          # push left
    lt          # push to
    0           # push processed marker 0
]se

[ # code block <x>
    ln 1 =M
    ln 1 !=d
]sx

[ # code block <y>
    lMx
    lex
]sy

[ # quit()
    q           # exit the program
]sq

[ # run()
    d 9 =q      # if stack empty, quit()
    sp          # processed
    st          # to
    sf          # from
    sn          # n
    6           #
    lf          #
    -           #
    lt          #
    -           # 6 - from - to
    sl          #
    lp 0 =x     #
    lp 0 !=y    #
    lrx         # loop
]sr

lix # init(n)
lrx # run()