RosettaCodeData/Task/Perfect-shuffle/Modula-2/perfect-shuffle.mod2

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MODULE PerfectShuffle;
FROM FormatString IMPORT FormatString;
FROM Storage IMPORT ALLOCATE,DEALLOCATE;
FROM SYSTEM IMPORT ADDRESS,TSIZE;
FROM Terminal IMPORT WriteString,WriteLn,ReadChar;
PROCEDURE WriteCard(c : CARDINAL);
VAR buf : ARRAY[0..15] OF CHAR;
BEGIN
FormatString("%c", buf, c);
WriteString(buf)
END WriteCard;
PROCEDURE Init(VAR arr : ARRAY OF INTEGER);
VAR i : CARDINAL;
BEGIN
FOR i:=0 TO HIGH(arr) DO
arr[i] := i + 1
END
END Init;
PROCEDURE PerfectShuffle(VAR arr : ARRAY OF INTEGER);
PROCEDURE Inner(ti : CARDINAL);
VAR
tv : INTEGER;
tp,tn,n : CARDINAL;
BEGIN
n := HIGH(arr);
tn := ti;
tv := arr[ti];
REPEAT
tp := tn;
IF tp MOD 2 = 0 THEN
tn := tp / 2
ELSE
tn := (n+1)/2+tp/2
END;
arr[tp] := arr[tn];
UNTIL tn = ti;
arr[tp] := tv
END Inner;
VAR
done : BOOLEAN;
i,c : CARDINAL;
BEGIN
c := 0;
Init(arr);
REPEAT
i := 1;
WHILE i <= (HIGH(arr)/2) DO
Inner(i);
INC(i,2)
END;
INC(c);
done := TRUE;
FOR i:=0 TO HIGH(arr) DO
IF arr[i] # INT(i+1) THEN
done := FALSE;
BREAK
END
END
UNTIL done;
WriteCard(HIGH(arr)+1);
WriteString(": ");
WriteCard(c);
WriteLn
END PerfectShuffle;
(* Main *)
VAR
v8 : ARRAY[1..8] OF INTEGER;
v24 : ARRAY[1..24] OF INTEGER;
v52 : ARRAY[1..52] OF INTEGER;
v100 : ARRAY[1..100] OF INTEGER;
v1020 : ARRAY[1..1020] OF INTEGER;
v1024 : ARRAY[1..1024] OF INTEGER;
v10000 : ARRAY[1..10000] OF INTEGER;
BEGIN
PerfectShuffle(v8);
PerfectShuffle(v24);
PerfectShuffle(v52);
PerfectShuffle(v100);
PerfectShuffle(v1020);
PerfectShuffle(v1024);
PerfectShuffle(v10000);
ReadChar
END PerfectShuffle.