Towers of Hanoi: Difference between revisions

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===version 2===

This version pictorially shows the moves for solving the Town of Hanoi.

<br>

Quite a bit of code has been dedicated to showing a picture of the

towers with the disks on them, and the movement of the disk (the move).

<br>

In addition, it shows each move in a countdown manner (the last move is

move #1).

<br>

No attempt is mode to explain this REXX code because of the complexity

and somewhat obtuse features of the REXX language, the smallest of which

is support for ASCII and EBCDIC "graphic" characters.

</lang>

/*REXX program pictorially shows moves for solving the Tower of Hanoi. */

arg z .

if z=='' then z=3

sw=80

wp=sw%3-1

c.1=sw%3%2

c.2=sw%2-1

c.3=sw-1-c.1-1

move=0

totmoves=2**z-1

movek=totmoves

lentot=length(totmoves)

@abc='abcdefghijklmnopqrstuvwxyz'

ebcdic='f0'x==0

if ebcdic then do

bar='bf'x;ar='df'x;boxen='db9f9caf'x;tl='ac'x;tr='bf'x;bl='ab'x;br='bb'x;vert='fa'x;down='9a'x

end

else do

bar='c4'x;ar='10'x;boxen='b0b1b2db'x;tl='da'x;tr='bf'x;bl='c0'x;br='d9'x;vert='b3'x;down='19'x

end

verts=vert||vert

downs=down||down

Tcorners=tl||tr

Bcorners=bl||br

box=left(boxen,1)

boxchars=boxen||@abc

bararrow=bar||bar||ar

$.1=z

$.2=0

$.3=0

k=z

kk=k+k

blanks=centre('',wp)

call sayhdr 1

do j=1 for z

@.3.j=blanks

@.2.j=blanks

@.1.j=centre(copies(box,kk),wp)

if z<=length(boxchars) then @.1.j=,

translate(@.1.j,substr(boxchars,kk%2,1),box)

kk=kk-2

end

call showtowers

call mov 1,3,z

call sayhdr 2

exit

/*─────────────────────────────MOV subroutine───────────────────────────*/

mov: if arg(3)==1 then call rng arg(1) arg(2)

else do

call mov arg(1),6-arg(1)-arg(2),arg(3)-1

call mov arg(1),arg(2),1

call mov 6-arg(1)-arg(2),arg(2),arg(3)-1

end

return

/*─────────────────────────────RNG subroutine───────────────────────────*/

rng: parse arg from dest

move=move+1

pp=

if from==1 then do

pp=overlay(bl,pp,c.1)

pp=overlay(bar,pp,c.1+1,c.dest-c.1-1,bar)

pp=pp||tr

end

if from==3 then do

pp=overlay(br,pp,c.3)

pp=overlay(bar,pp,c.dest+1,c.3-c.dest-1,bar)

pp=overlay(tl,pp,c.dest)

end

if from==2 then do

lpost=min(2,dest)

hpost=max(2,dest)

if dest==1 then do

pp=overlay(tl,pp,c.1)

pp=overlay(bar,pp,c.1+1,c.2-c.1-1,bar)

pp=pp||br

end

if dest==3 then do

pp=overlay(bl,pp,c.2)

pp=overlay(bar,pp,c.2+1,c.3-c.2-1,bar)

pp=pp||tr

end

end

say translate(pp,verts,Bcorners||Tcorners||bar)

say overlay(movek,pp,1)

say translate(pp,verts,Tcorners||Bcorners||bar)

say translate(pp,downs,Tcorners||Bcorners||bar)

movek=movek-1

$.from=$.from-1

$.dest=$.dest+1

_f=$.from+1

_t=$.dest

@.dest._t=@.from._f

@.from._f=blanks

call showtowers

return

/*═════════════════════════════general 1-line subs══════════════════════*/

sayhdr:parse arg x;if x==1 then call saysep;call sayMinMov;say;if x==2 then call saysep;return

sayMinMov:say

_="The minimum number of moves for a" z 'ring Tower of Hanoi is'

say centre(_ totmoves,sw-1,bar);return

saysep:say copies(bar,sw-1);return

showtowers:do j=z to 1 by -1;_p=@.1.j @.2.j @.3.j;if _p\='' then say _p;end;return

</lang>

Output:

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