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|
#! /bin/bash
# The Towers Of Hanoi
# Original script (hanoi.bash) copyright (C) 2000 Amit Singh.
# All Rights Reserved.
# http://hanoi.kernelthread.com
# hanoi2.bash
# Version 2.00: modded for ASCII-graphic display.
# Version 2.01: fixed no command-line param bug.
# Uses code contributed by Antonio Macchi,
#+ with heavy editing by ABS Guide author.
# This variant falls under the original copyright, see above.
# Used in ABS Guide with Amit Singh's permission (thanks!).
### Variables && sanity check ###
E_NOPARAM=86
E_BADPARAM=87 # Illegal no. of disks passed to script.
E_NOEXIT=88
DISKS=${1:-$E_NOPARAM} # Must specify how many disks.
Moves=0
MWIDTH=7
MARGIN=2
# Arbitrary "magic" constants; work okay for relatively small # of disks.
# BASEWIDTH=51 # Original code.
let "basewidth = $MWIDTH * $DISKS + $MARGIN" # "Base" beneath rods.
# Above "algorithm" could likely stand improvement.
### Display variables ###
let "disks1 = $DISKS - 1"
let "spaces1 = $DISKS"
let "spaces2 = 2 * $DISKS"
let "lastmove_t = $DISKS - 1" # Final move?
declare -a Rod1 Rod2 Rod3
### ######################### ###
function repeat { # $1=char $2=number of repetitions
local n # Repeat-print a character.
for (( n=0; n<$2; n++ )); do
echo -n "$1"
done
}
function FromRod {
local rod summit weight sequence
while true; do
rod=$1
test ${rod/[^123]/} || continue
sequence=$(echo $(seq 0 $disks1 | tac))
for summit in $sequence; do
eval weight=\${Rod${rod}[$summit]}
test $weight -ne 0 &&
{ echo "$rod $summit $weight"; return; }
done
done
}
function ToRod { # $1=previous (FromRod) weight
local rod firstfree weight sequence
while true; do
rod=$2
test ${rod/[^123]} || continue
sequence=$(echo $(seq 0 $disks1 | tac))
for firstfree in $sequence; do
eval weight=\${Rod${rod}[$firstfree]}
test $weight -gt 0 && { (( firstfree++ )); break; }
done
test $weight -gt $1 -o $firstfree = 0 &&
{ echo "$rod $firstfree"; return; }
done
}
function PrintRods {
local disk rod empty fill sp sequence
repeat " " $spaces1
echo -n "|"
repeat " " $spaces2
echo -n "|"
repeat " " $spaces2
echo "|"
sequence=$(echo $(seq 0 $disks1 | tac))
for disk in $sequence; do
for rod in {1..3}; do
eval empty=$(( $DISKS - (Rod${rod}[$disk] / 2) ))
eval fill=\${Rod${rod}[$disk]}
repeat " " $empty
test $fill -gt 0 && repeat "*" $fill || echo -n "|"
repeat " " $empty
done
echo
done
repeat "=" $basewidth # Print "base" beneath rods.
echo
}
display ()
{
echo
PrintRods
# Get rod-number, summit and weight
first=( `FromRod $1` )
eval Rod${first[0]}[${first[1]}]=0
# Get rod-number and first-free position
second=( `ToRod ${first[2]} $2` )
eval Rod${second[0]}[${second[1]}]=${first[2]}
echo; echo; echo
if [ "${Rod3[lastmove_t]}" = 1 ]
then # Last move? If yes, then display final position.
echo "+ Final Position: $Moves moves"; echo
PrintRods
fi
}
# From here down, almost the same as original (hanoi.bash) script.
dohanoi() { # Recursive function.
case $1 in
0)
;;
*)
dohanoi "$(($1-1))" $2 $4 $3
if [ "$Moves" -ne 0 ]
then
echo "+ Position after move $Moves"
fi
((Moves++))
echo -n " Next move will be: "
echo $2 "-->" $3
display $2 $3
dohanoi "$(($1-1))" $4 $3 $2
;;
esac
}
setup_arrays ()
{
local dim n elem
let "dim1 = $1 - 1"
elem=$dim1
for n in $(seq 0 $dim1)
do
let "Rod1[$elem] = 2 * $n + 1"
Rod2[$n]=0
Rod3[$n]=0
((elem--))
done
}
### Main ###
setup_arrays $DISKS
echo; echo "+ Start Position"
case $# in
1) case $(($1>0)) in # Must have at least one disk.
1)
disks=$1
dohanoi $1 1 3 2
# Total moves = 2^n - 1, where n = number of disks.
echo
exit 0;
;;
*)
echo "$0: Illegal value for number of disks";
exit $E_BADPARAM;
;;
esac
;;
*)
clear
echo "usage: $0 N"
echo " Where \"N\" is the number of disks."
exit $E_NOPARAM;
;;
esac
exit $E_NOEXIT # Shouldn't exit here.
# Note:
# Redirect script output to a file, otherwise it scrolls off display.
|
