AI : dog rabbit carrots rivercrosing try

[bluatigro]

i want to solve thge folowing puzzle :

a farmer has a dog a rabbit and carrots

he wants to cross a river

there is a boot
but it can only carry the farmer and one item
the dog wil kil the rabbit when left alone on one shore
the rabbit wil eat the carrots when left alone on one shore

my chalence : write a program that solves this puzzle

first try : using rnd

global dog , rabbit , carrots

global shore.begin , shore.end

dog = 1

rabbit = 2

carrots = 4



shore.begin = dog + rabbit + carrots

shore.end = 0



while shore.begin

 scan

 dice = irange( 0 , 3 )

 select case dice

   case 0

     if shore.begin and dog then

       shore.begin = shore.begin - dog

       if issave( shore.begin ) then

         shore.end = shore.end + dog

         print "farmer moves dog ."

       else

         shore.begin = shore.begin + dog

       end if

     end if

   case 1

     if shore.begin and rabbit then

       shore.begin = shore.begin - rabbit

       if issave( shore.begin ) then

         shore.end = shore.end + rabbit

         print "farmer moves rabbit ."

       else

         shore.begin = shore.begin + rabbit

       end if

     end if

   case 2

     if shore.begin and carrots then

       shore.begin = shore.begin - carrots

       if issave( shore.begin ) then

         shore.end = shore.end + carrots

         print "farmer moves carrots ."

       else

         shore.begin = shore.begin + carrots

       end if

     end if

   case else

     if issave( shore.begin ) then

       print "farmer moves nothing ."

     end if

 end select

 dice = irange( 0 , 3 )

 select case dice

   case 0

     if shore.end and dog then

       shore.end = shore.end - dog

       if issave( shore.end ) then

         shore.begin = shore.begin + dog

         print "farmer moves dog back ."

       else

         shore.end = shore.end + dog

       end if

     end if

   case 1

     if shore.end and rabbit then

       shore.end = shore.end - rabbit

       if issave( shore.end ) then

         shore.begin = shore.begin + rabbit

         print "farmer moves rabbit back ."

       else

         shore.end = shore.end + rabbit

       end if

     end if

   case 0

     if shore.end and carrots then

       shore.end = shore.end - carrots

       if issave( shore.end ) then

         shore.begin = shore.begin + rarrots

         print "farmer moves dog back"

       else

         shore.end = shore.end + dog

       end if

     end if

   case else

     if issave( shore.end ) then

       print "farmer moves nothing back ."

     end if

 end select

wend

print "puzzle solved !!"



end

function irange( low , high )

 irange = int( rnd(0) * ( high - low + 1 ) ) + low

end function

function issave( shore )

 a = ( shore and ( dog + rabbit ) )

 b = ( shore and ( rabbit + carrots ) )

 issave = not( a or b )

end function




[Rod]

We had something similar a while ago.

1)take rabbit
2)return
3)take carrot
4)return with rabbit
5)take dog
6)return
7)take rabbit



'This code builds a sequence of moves
'if the sequence remains valid it will
'be built on and other moves tried
'if any prove invalid the sequence is abandoned
direction$="<"
dim option$(100,4) 'left,right,status,previous
option$(1,1)="RCD"
option$(1,2)=""
option$(1,3)="?"
option$(1,4)="1,"
optnum=1
nextopt=2
left=1
right=2
status=3
previous=4

[move]

if direction$="<" then direction$=">" else direction$="<"

   for opt=1 to nextopt-1

       if option$(opt,status)="?" then

           [select]
           if direction$=">" then

               'left to right
               'run all movement options left set to right set
               for n= 1 to len(option$(opt,left))
                   take$=mid$(option$(opt,left),n,1)
                   leave$=""
                   for m= 1 to len(option$(opt,left))
                       if m<>n then leave$=leave$+mid$(option$(opt,left),m,1)
                   next

                   'now check if the remaining combination is valid
                   'its what is left behind that is important as the farmer
                   'moves to the new location

                   select case allowed(leave$,direction$)

                       case 1
                       'if it is valid create a new option
                       option$(nextopt,left)=leave$
                       option$(nextopt,right)=option$(opt,right)+take$
                       option$(nextopt,status)="?"
                       option$(nextopt,previous)=option$(opt,previous)+str$(nextopt)+","
                       gosub [printit]


                       case 2
                       'if we have achieved success stop
                       option$(nextopt,left)=leave$
                       option$(nextopt,right)=option$(opt,right)+take$
                       option$(nextopt,status)="?"
                       option$(nextopt,previous)=option$(opt,previous)+str$(nextopt)+","
                       gosub [printit]
                       print "Success"
                       end

                       'case else
                       'gosub [printit]

                   end select
               next

           else

               'right to left
               'run all movement options right set to left set

               for n= 1 to len(option$(opt,right))
                   take$=mid$(option$(opt,right),n,1)
                   leave$=""
                   for m= 1 to len(option$(opt,right))
                       if m<>n then leave$=leave$+mid$(option$(opt,right),m,1)
                   next

                   'now check if the remaining combination is valid

                   select case allowed(leave$,direction$)

                       case 1
                       'if it is valid create a new option
                       option$(nextopt,right)=leave$
                       option$(nextopt,left)=option$(opt,left)+take$
                       option$(nextopt,status)="?"
                       option$(nextopt,previous)=option$(opt,previous)+str$(nextopt)+","
                       gosub [printit]

                       case 2
                       'if we have achieved success stop
                       option$(nextopt,right)=leave$
                       option$(nextopt,left)=option$(opt,left)+take$
                       option$(nextopt,status)="?"
                       option$(nextopt,previous)=option$(opt,previous)+str$(nextopt)+","
                       gosub [printit]
                       print "Success"
                       end
                   end select

                   'now create the option to take nothing, just move the farmer left
                   'but only if that leaves a valid combination
                   if allowed(option$(opt,right),direction$) then
                       option$(nextopt,right)=option$(opt,right)
                       option$(nextopt,left)=option$(opt,left)
                       option$(nextopt,status)="?"
                       option$(nextopt,previous)=option$(opt,previous)+str$(nextopt)+","
                       take$="0"
                       gosub [printit]
                   end if

               next

           end if

           option$(opt,status)="X"

       end if

   next

goto [move]

[printit]
   print nextopt;" ";option$(opt,left);"/";option$(opt,right),direction$;
   print " Take ";take$,
   print option$(nextopt,left);"/";option$(nextopt,right);" ";option$(nextopt,previous)
   nextopt=nextopt+1
   return



function allowed(l$,d$) '0=not allowed, 1=allowed, 2=game over
   select case
       case d$=">" and l$=""
       allowed=2
       case len(l$)=1
       allowed=1
       case len(l$)=3
       allowed=0
       case l$="CR" or l$="RC"
       allowed=0
       case l$="DR" or l$="RD"
       allowed=0
       case else
       allowed=1
   end select
end function