Tic-tac-toe: Difference between revisions

=={{Header|Tiny BASIC}}==

<lang Tiny BASIC> REM Tic-tac-toe for Tiny BASIC

REM

REM Released as public domain by Damian Gareth Walker, 2019

REM Created: 21-Sep-2019

REM --- Variables

REM A - first square in line examined

REM B - second square in line examined

REM C - third square in line examined

REM D - player whose pieces to count

REM E - number of DREM s pieces on a line

REM F - first square of line to examine

REM G - game winner

REM H - which side the human takes

REM I - increment for line to examine

REM L - line to examine

REM M - where to move (various uses)

REM N - piece found in a square

REM P - player currently playing

REM Q - square to examine

REM R-Z - contents of the board

REM --- Main Program

GOSUB 40

GOSUB 60

GOSUB 80

END

REM --- Subroutine to initialise the game

REM Outputs: H - Human play order

REM P - Whose turn it is

40 PRINT "Tic tac toe. Board positions are:"

PRINT " 1 2 3"

PRINT " 4 5 6"

PRINT " 7 8 9"

PRINT "Play first or second (1/2)?"

INPUT H

IF H<1 THEN GOTO 40

IF H>2 THEN GOTO 40

LET P=1

RETURN

REM --- Subroutine to take turns

REM Inputs: H - who is the human

REM P - whose turn it is

REM Outputs: G - who won the game

60 IF P=H THEN GOSUB 100

IF P<>H THEN GOSUB 120

GOSUB 200

IF G>0 THEN RETURN

LET P=3-P

IF R=0 THEN GOTO 60

IF S=0 THEN GOTO 60

IF T=0 THEN GOTO 60

IF U=0 THEN GOTO 60

IF V=0 THEN GOTO 60

IF W=0 THEN GOTO 60

IF X=0 THEN GOTO 60

IF Y=0 THEN GOTO 60

IF Z=0 THEN GOTO 60

RETURN

REM --- Victory

REM Inputs: H - which side was the human

REM P - player who won

80 IF G=H THEN PRINT "You win!"

IF G<>0 THEN IF G<>H THEN PRINT "Computer wins"

IF G=0 THEN PRINT "A draw"

RETURN

REM --- Subroutine to allow the player to move

REM Inputs: P - player number

REM Outputs: M - where the player wishes to move

100 PRINT "Move? "

INPUT Q

IF Q<1 THEN GOTO 100

IF Q>9 THEN GOTO 100

GOSUB 220

IF N<>0 THEN GOTO 100

LET M=Q

GOSUB 240

RETURN

REM --- Subroutine to make the computerREM s move

REM Inputs: P - player number

REM Outputs: M - the move chosen

120 LET M=0

LET D=3-H

GOSUB 145

IF M>0 THEN GOTO 135

LET D=H

GOSUB 145

IF M=0 THEN IF V=0 THEN LET M=5

IF M=0 THEN IF R=0 THEN LET M=1

IF M=0 THEN IF T=0 THEN LET M=3

IF M=0 THEN IF X=0 THEN LET M=7

IF M=0 THEN IF Z=0 THEN LET M=9

IF M=0 THEN IF S=0 THEN LET M=2

IF M=0 THEN IF U=0 THEN LET M=4

IF M=0 THEN IF Y=0 THEN LET M=8

IF M=0 THEN IF W=0 THEN LET M=6

135 GOSUB 240

PRINT "Computer move ",M

RETURN

REM --- Identify moves to win or avoid a loss

REM Inputs: D - player whose pieces weREM re counting

REM Changes: E - number of pieces on line being scanned

REM F - first square in winning line

REM I - increment of winning line

REM L - line being scanned (counter)

145 LET L=1

146 GOSUB 170

IF E<2 THEN GOTO 152

IF A=0 THEN LET M=F

IF B=0 THEN LET M=F+I

IF C=0 THEN LET M=F+I+I

IF M>0 THEN RETURN

152 LET L=L+1

IF L<9 THEN GOTO 146

RETURN

REM --- Count a playerREM s pieces on a line

REM Inputs: D - player whose pieces weREM re counting

REM L - line number

REM Changes: F - first square on the line

REM I - increment of the line

REM Q - individual squares to examine

REM Outputs: A - contents of first square

REM B - contents of second square

REM C - contents of third square

REM E - number of the playerREM s pieces

170 IF L>3 THEN GOTO 174

LET F=3*L-2

LET I=1

GOTO 180

174 IF L>6 THEN GOTO 178

LET F=L-3

LET I=3

GOTO 180

178 LET F=1+2*(L-7)

LET I=4-2*(L-7)

180 LET E=0

LET Q=F

GOSUB 220

LET A=N

IF N=D THEN LET E=E+1

LET Q=Q+I

GOSUB 220

LET B=N

IF N=D THEN LET E=E+1

LET Q=Q+I

GOSUB 220

LET C=N

IF N=D THEN LET E=E+1

RETURN

REM --- Subroutine to check for a win

REM Inputs: R-Z - board squares

REM Outputs: G - the winning player (0 for neither)

200 LET G=0

IF R>0 THEN IF R=S THEN IF S=T THEN LET G=R

IF U>0 THEN IF U=V THEN IF V=W THEN LET G=U

IF X>0 THEN IF X=Y THEN IF Y=Z THEN LET G=X

IF R>0 THEN IF R=U THEN IF U=X THEN LET G=R

IF S>0 THEN IF S=V THEN IF V=Y THEN LET G=S

IF T>0 THEN IF T=W THEN IF W=Z THEN LET G=T

IF R>0 THEN IF R=V THEN IF V=Z THEN LET G=R

IF T>0 THEN IF T=V THEN IF V=X THEN LET G=T

RETURN

REM --- Subroutine to see what piece is in a square

REM Inputs: Q - the square to check

REM R-Z - the contents of the squares

REM Outputs: N - the piece in that square

220 LET N=0

IF Q=1 THEN LET N=R

IF Q=2 THEN LET N=S

IF Q=3 THEN LET N=T

IF Q=4 THEN LET N=U

IF Q=5 THEN LET N=V

IF Q=6 THEN LET N=W

IF Q=7 THEN LET N=X

IF Q=8 THEN LET N=Y

IF Q=9 THEN LET N=Z

RETURN

REM --- Subroutine to put a piece in a square

REM Inputs: P - the player whose piece should be placed

REM M - the square to put the piece in

REM Changes: R-Z - the contents of the squares

240 IF M=1 THEN LET R=P

IF M=2 THEN LET S=P

IF M=3 THEN LET T=P

IF M=4 THEN LET U=P

IF M=5 THEN LET V=P

IF M=6 THEN LET W=P

IF M=7 THEN LET X=P

IF M=8 THEN LET Y=P

IF M=9 THEN LET Z=P

RETURN </lang>