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Langton's ant: Difference between revisions

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Langton's ant (view source)

Revision as of 23:18, 2 June 2020

3 bytes removed ,  4 years ago
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m (→‎{{header|REXX}}: added whitespace.)
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parse arg dir char seed . /*obtain optional arguments from the CL*/
if datatype(seed, 'W') then call random ,,seed /*Integer? Then use it as a RANDOM SEED*/
if dir=='' | dir=="," then dir= random(1, 4) /*ant is facing a random direction, */
if char=='' | char=="," then char= '#' /*binary colors: 0≡white, 1≡black. */
parse value scrSize() with sd sw . /*obtain the terminal's depth and width*/
sd= sd -6; sw= sw -1 /*adjust for terminal's useableusable area. */
xHome= 1000000; yHome=1000000 1000000 /*initially in the middle of nowhere. */
x= xHome; y= yHome /*start ant's walk in middle of nowhere*/
$.= 1; ; $.0= 4 ; $.2= 2 ; $.3= 3; $.4= 4 /* 1≡north 2≡east 3≡south 4≡west.*/
minX= x; minY= y; maxX= x; maxY=y y /*initialize the min/max values for X,Y*/
@.=0 0 /*the universe (walk field) is white.*/
do #=1 until (maxX-minY>sw)|(maxY-minY>sd) /*is the path out─of─bounds for screen?*/
black= @.x.y; @.x.y= \@.x.y /*invert (flip) ant's cell color code.*/
if black then dir= dir - 1 /*if cell color was black, turn left.*/
else dir= dir + 1 /* " " " " white, turn right.*/
dir= $.dir /*$ array handles/adjusts under & over.*/
select /*ant walks the direction it's facing. */
when dir==1 then y= y + 1 /*is ant walking north? Then go up. */
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when dir==4 then x= x - 1 /* " " " west? " " left. */
end /*select*/ /*the DIRection is always normalized.*/
minX= min(minX, x); maxX= max(maxX, x) /*find the minimum and maximum of X. */
minY= min(minY, y); maxY= max(maxY, y) /* " " " " " " Y. */
end /*steps*/ /* [↑] ant walks hither and thither. */
/*finished walking, it's out─of─boundsout-of-bounds.*/
say center(" Langton's ant walked " # ' steps ', sw, "─")
@.xHome.yHome= '█' /*show the ant's initial starting point*/
@.x.y= '∙' /*show where the ant went out─of─bounds*/
/* [↓] show Langton's ant's trail. */
do y=maxY to minY by -1; _= /*display a single row of cells. */
do x=minX to maxX; _=_ || @.x.y /*build a cell row for the display. */
end /*x*/ /* [↓] strip trailing blanks from line*/
_= strip( translate(_, char, 10), 'T') /*color the cells: black or white. */
if _\=='' then say _ /*display line (strip trailing blanks).*/
end /*y*/ /*stick a fork in it, we're all done. */</lang>
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