Thue-Morse: Difference between revisions

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 |                   ; Repeat loop</lang>
 The standard DOS-based interpreter will display an error message about word too long after 7 lines are output; this is because the 8th line does not fit in 80 columns.
+=={{header|Pascal}}==
+{{works with|Free Pascal}}
+<lang pascal>
+Program ThueMorse;
+procedure NextThueMorse(var s: AnsiString);
+//double length and append by flipping every original 0 -> 1;1 -> 0
+//flipping x between A;B - > x_next = A+B-x
+var
+  i : NativeInt;
+  pOrg,
+  pRpl : pChar;
+Begin
+  IF s = '' then
+  Begin
+    s := '0';
+    EXIT;
+  end;
+  i := length(s);
+  setlength(s,i+i);
+  pOrg := @s[1];
+  pRpl := @s[i+1];
+  repeat
+    dec(i);
+    pRpl[i] := chr(Ord('1')+Ord('0')-Ord(pOrg[i]));
+  until i<=0;
+end;
+procedure NextThueMorseLSystem(var s: AnsiString);
+//double length and replace every 0 -> 01 and 1 -> 10
+//doing it backwards, so no extra copy is needed.
+const
+  cReplace : array['0'..'1'] of String[2] = ('01','10');
+var
+  i : NativeInt;
+  pS,pR : pChar;
+Begin
+  IF s = '' then
+  Begin
+    s := '0';
+    EXIT;
+  end;
+  i := length(s);
+  setlength(s,i+i);
+  pS := @s[i+i];
+  dec(ps);
+  repeat
+    pR := @cReplace[s[i]];
+    pS[ 1]:= pR[2];
+    pS[ 0]:= pR[1];
+    dec(ps,2);
+    dec(i);
+  until i<=0;
+end;
+var
+ s: AnsiString;
+ i : integer;
+Begin
+  For i := 0 to 30 do
+  Begin
+    NextThueMorse(s);
+    IF i < 6 then
+      writeln(s);
+  end;
+  writeln(length(s));
+end.</lang>
+{{Output}}<pre>//NextThueMorse
+01101001
+0110100110010110
+01101001100101101001011001101001
+1073741824 ( 1 GB)
+real  0m1.162s user  0m0.689s sys 0m0.472s //memory allocation
+//NextThueMorseLSystem
+Same Output
+real  0m1.981s user  0m1.492s sys 0m0.486s
+</pre>
 =={{header|Perl 6}}==
 {{Works with|rakudo|2015-12-22}}