REM Advent of Code 2022: Day 7, part 1 and 2 REM Written in Applesoft BASIC REM Usual initialization. SPEED= sets the text speed; I play with it REM and some empty FOR loops during the program for artistic effect. 10 ONERR GOTO 700 20 PRINT CHR$ (4),"OPEN INPUT" 30 PRINT CHR$ (4),"READ INPUT" 40 HOME 50 SPEED= 170 REM DN$ and DS are a index-matched "map" of paths and sizes. A size of REM 200 accommodated my input. REM W$ stores the current working directory. 100 DIM DN$(200) 110 DIM DS(200) 120 FOR I = 0 TO 199:DN$(I) = "": NEXT I 130 FOR I = 0 TO 199:DS(I) = 0: NEXT I 140 W$ = "/" REM Main loop: consume a line of input, display it, and then handle REM either the "ls" or "cd" that it is. 200 GOSUB 4000 210 PRINT "$"; 215 FOR I = 0 TO 1000: NEXT I 218 SPEED= 70: PRINT RIGHT$ (S$, LEN (S$) - 1): SPEED= 170 220 IF LEFT$ (S$,4) = "$ cd" GOTO 300 230 GOTO 500 REM "cd" routine. If the path starts with '/', then clear the working REM directory so we return to root. REM If starting with a '.', GOTO 350 to handle backing up a level. REM Otherwise, append to the working directory. 300 C$ = MID$ (S$,6,1) 305 IF ASC (C$) = 47 THEN W$ = "" 310 IF ASC (C$) = 46 GOTO 350 320 W$ = W$ + MID$ (S$,6, LEN (S$) - 5) 330 IF ASC ( RIGHT$ (W$,1)) < > 47 THEN W$ = W$ + "/" 340 GOTO 400 350 W$ = LEFT$ (W$, LEN (W$) - 1) 360 IF RIGHT$ (W$,1) < > "/" GOTO 350 370 GOTO 200 REM Call 2000 to create a size entry for this directory if it does not REM exist. 400 S$ = W$ 410 GOSUB 2000 420 GOTO 200 REM "ls" routine. Leave the loop if we reach the next command; skip dirs. 500 V = 0 510 GOSUB 4000 515 IF LEFT$ (S$,1) = "$" GOTO 210 520 PRINT S$ 530 IF LEFT$ (S$,3) = "dir" GOTO 510 REM Call 3000 to add file's size to relevant directorys' totals. 540 V = VAL (S$) 550 S$ = W$ 560 GOSUB 3000 570 GOTO 510 REM We will land here once the file has been completely read. Do the REM search for part 1, summing into T. 700 T = 0 710 FOR I = 0 TO 199 720 IF LEN (DN$(I)) = 0 THEN I = 199: GOTO 740 730 IF DS(I) < = 100000 THEN T = T + DS(I) 740 NEXT I 745 PRINT 750 PRINT "part 1: ";T;" bytes" REM Part 2 is at 5000. It will come back to 900 to exit. 760 GOTO 5000 900 PRINT CHR$ (4),"CLOSE" 910 SPEED= 255 920 END REM Subroutine: Fetches the size of directory S$, putting it in V. 1000 V = 0 1010 FOR I = 0 TO 199 1020 IF DN$(I) = S$ THEN V = DS(I):I = 199 1030 NEXT I 1040 RETURN REM Subroutine: Initializes new entry for directory S$. 2000 FOR I = 0 TO 199 2010 IF DN$(I) = S$ THEN PRINT "ERROR": END 2020 IF LEN (DN$(I)) = 0 THEN DN$(I) = S$:DS(I) = 0:I = 199 2030 NEXT I 2040 RETURN REM Subroutine: Adds size V to entry for directory S$ and its parents. 3000 FOR I = 0 TO 199 3010 L = LEN (S$) 3015 M = LEN (DN$(I)) 3020 IF LEN (DN$(I)) = 0 THEN I = 199: GOTO 3040 3030 IF L > = M AND LEFT$ (S$,M) = DN$(I) GOTO 3060 3040 NEXT I 3050 RETURN 3060 DS(I) = DS(I) + V 3080 GOTO 3040 REM Subroutine: Reads next line of input from the file. 4000 S$ = "" 4010 GET C$ 4020 IF ASC (C$) < 32 GOTO 4050 4030 S$ = S$ + C$ 4040 GOTO 4010 4050 RETURN REM Part 2. Start by printing total filesystem size. 5000 PRINT "$ "; 5002 SPEED= 70: PRINT "df -h": SPEED= 170 5004 FOR I = 0 TO 1000: NEXT I 5006 S$ = "/" 5010 GOSUB 1000 5015 PRINT V REM Calculate free memory requirements. 5020 UN = 70000000 - V 5030 RE = 30000000 - UN 5040 DE = 99999999 5100 PRINT "$"; 5110 SPEED= 70: PRINT " cleanup": SPEED= 170 5120 FOR I = 0 TO 1000: NEXT I 5130 PRINT "NEED TO FREE ";RE;" BYTES..." REM The actual work: iterate for smallest entry that is at least RE bytes. 5200 FOR I = 0 TO 199 5210 IF LEN (DN$(I)) = 0 THEN I = 199: GOTO 5230 5220 IF DS(I) > RE AND DS(I) < DE THEN DE = DS(I) 5230 NEXT I REM All done! 5240 PRINT "FREED ";DE;" BYTES." 5250 GOTO 900 REM Debug subroutine: print all contents of directory/size map. 6000 FOR I = 0 TO 199 6010 IF LEN (DN$(I)) = 0 THEN I = 199: GOTO 6030 6020 PRINT DN$(I),DS(I) 6030 NEXT I 6040 RETURN