!Takoma Park M.S.

!ACSL Jr. div

!Joel Muskin-Pieret

!

DO

LINE INPUT prompt "node list: ":nodes$

LET length = len(nodes$)

LET a = (length-3)/4

DIM x(100)

DIM y(100)

IF not(val(nodes$[length:length]) = 0 and val(nodes$[length-2:length-2]) = 0) then

PRINT "Node list invalid (does not end with 0,0)"

END IF

LOOP until val(nodes$[length:length]) = 0 and val(nodes$[length-2:length-2]) = 0

FOR b = 1 to a

LET x(b) = val(nodes$[4*b -3:4*b -3])

LET y(b) = val(nodes$[4*b -1:4*b -1])

NEXT b

LET c = 0

LET d = 0

FOR b = 1 to a

IF x(b) > c then LET c = x(b)

IF y(b) > d then LET d = y(b)

NEXT b

DIM graph(30,30)

DIM visited(30,30)

FOR f = 1 to 30

FOR g = 1 to 30

LET graph(f,g) = 0

LET visited(f,g) = 0

NEXT g

NEXT f

FOR b = 1 to a

LET graph(x(b),y(b)) = 1

LET visited(x(b),y(b)) = 1

NEXT b

DIM listx(100)

DIM listy(100)

DO

INPUT prompt "start and end points (0,0,0,0 to end): ": sx, sy, ex, ey

IF sx > 0 and sy > 0 and ex > 0 and ey > 0 then

LET listx(1)=sx

LET listy(1)=sy

LET c = 1

LET finish = 0

LET output$ = ""

FOR az = 1 to 30

FOR b = 1 to 30

LET visited(az,b) = graph(az,b)

NEXT b

NEXT az

LET visited(sx,sy) = 2

IF sx <> ex and sy <> ey then

DO

LET d = 0

LET e = 0

FOR az = -1 to 1

FOR b = -1 to 1

IF az <> 0 or b <> 0 then

IF listx(c) + az > 0 and listy(c)+b > 0 then

IF visited(listx(c) + az,listy(c)+b) = 1 and e = 0 and c > 0 then

LET c = c + 1

LET e = 1

LET listx(c) = listx(c-1) + az

LET listy(c) = listy(c-1) + b

LET visited(listx(c-1) + az,listy(c-1)+b) = 2

ELSE

LET d = d + 1

END IF

ELSE

LET d = d + 1

END IF

END IF

NEXT b

NEXT az

IF d = 8 and c > 0 then

LET listx(c) = 0

LET listy(c) = 0

LET c = c - 1

END IF

IF c > 0 then

IF listx(c) = ex and listy(c) = ey then

LET finish = 1

END IF

END IF

LOOP until c = 0 or finish = 1

END IF

IF c = 0 then

PRINT "NONE"

ELSE IF c > 1 then

FOR b = 1 to c-1

LET output$ = output$ & str$(listx(b)) & ","

LET output$ = output$ & str$(listy(b)) & ","

NEXT b

LET output$ = output$ & str$(listx(c)) & "," & str$(listy(c))

PRINT output$

ELSE

LET output$ = output$ & str$(listx(c)) & "," & str$(listy(c))

PRINT output$

END IF

END IF

LOOP until sx = 0 and sy = 0 and ex = 0 and ey = 0

END