Langton's ant: Difference between revisions
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(→{{header|REXX}}: added comments, DO-END labels, remove superflous blanks. -- ~~~~) |
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=={{header|REXX}}== |
=={{header|REXX}}== |
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<lang rexx>/*REXX program implements Langton's ant and displays it's walk(s). */ |
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<lang rexx> |
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/*Langton's ant*/ |
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parse arg dir . /*allow specification: ant facing*/ |
parse arg dir . /*allow specification: ant facing*/ |
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/*binary colors: 0=white, 1=black*/ |
/*binary colors: 0=white, 1=black*/ |
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@.=0 /*define stem array (all white).*/ |
@.=0 /*define stem array (all white).*/ |
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lb= |
lb=1 ; rb=100 /* right boundry, right boundry.*/ |
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bb= |
bb=1 ; tb=100 /*bottom boundry, top boundry.*/ |
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x=(rb-lb)%2 ; y=(tb-bb)%2 /*approximate center (walk start)*/ |
x=(rb-lb)%2 ; y=(tb-bb)%2 /*approximate center (walk start)*/ |
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if dir=='' then dir=random(1,4) /*ant is facing random direction,*/ |
if dir=='' then dir=random(1,4) /*ant is facing random direction,*/ |
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/*1=north 2=east 3=south 4=west*/ |
/*1=north 2=east 3=south 4=west*/ |
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/*───────────────────────────────────────────ant walks hither & thither.*/ |
/*───────────────────────────────────────────ant walks hither & thither.*/ |
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do steps=1 until x<lb | x>rb | y<bb | y>tb /*walk until out-of-bounds*/ |
do steps=1 until x<lb | x>rb | y<bb | y>tb /*walk until out-of-bounds*/ |
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black=@.x.y /*get color code of ant's cell. */ |
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@.x.y=\@.x.y /*change the color of the cell. */ |
@.x.y=\@.x.y /*change the color of the cell. */ |
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if |
if black then dir=dir-1 /*if cell was black, turn left. */ |
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else dir=dir+1 |
else dir=dir+1 /*if cell was white, turn right. */ |
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if dir==0 then dir=4 /*ant should be facing "west". */ |
if dir==0 then dir=4 /*ant should be facing "west". */ |
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if dir==5 then dir=1 /*and should be facing "north". */ |
if dir==5 then dir=1 /*and should be facing "north". */ |
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when dir==3 then y=y-1 /*walking south? Then go "down".*/ |
when dir==3 then y=y-1 /*walking south? Then go "down".*/ |
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when dir==4 then x=x-1 /*walking west? Then go "left".*/ |
when dir==4 then x=x-1 /*walking west? Then go "left".*/ |
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end |
end /*select*/ |
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end |
end /*steps*/ |
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/*───────────────────────────────────────────────display the ant's walk.*/ |
/*───────────────────────────────────────────────display the ant's walk.*/ |
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say "──────── Langton's ant walked" steps 'steps. ────────' |
say "──────── Langton's ant walked" steps 'steps. ────────'; say |
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say |
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do minx=lb to rb /*find the leftest black column.*/ |
do minx=lb to rb /*find the leftest black column.*/ |
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do y=bb to tb /*search row by row for it. */ |
do y=bb to tb /*search row by row for it. */ |
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if @.minx.y then leave minx /*found one, now quit searching.*/ |
if @.minx.y then leave minx /*found one, now quit searching.*/ |
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end |
end /*y*/ |
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end |
end /*minx*/ /*above code crops left of array*/ |
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do y=tb to bb by -1; _='' /*display a plane (row) of cells*/ |
do y=tb to bb by -1; _='' /*display a plane (row) of cells*/ |
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do x=minx to rb /*process a "row" of cells. */ |
do x=minx to rb /*process a "row" of cells. */ |
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_=_||@.x.y /*build a cell row for display. */ |
_=_||@.x.y /*build a cell row for display. */ |
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end |
end /*x*/ |
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_=translate(_,'#',10) /*color the cells: black | white*/ |
_=translate(_,'#',10) /*color the cells: black | white*/ |
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if _\='' then say strip(_,'T') /*crop completely white lines. */ |
if _\='' then say strip(_,'T') /*crop completely white lines. */ |
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end |
end /*y*/</lang> |
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'''output''' |
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</lang> |
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Output |
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<pre style="height:60ex;overflow:scroll"> |
<pre style="height:60ex;overflow:scroll"> |
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──────── Langton's ant walked 11759 steps. ──────── |
──────── Langton's ant walked 11759 steps. ──────── |
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