Pascal's triangle: Difference between revisions

=={{header|Component Pascal}}==

{{Works with|BlackBox Component Builder}}

<lang oberon2>

MODULE PascalTriangle;

IMPORT StdLog, DevCommanders, TextMappers;

TYPE

Expansion* = POINTER TO ARRAY OF LONGINT;

PROCEDURE Show(e: Expansion);

VAR

i: INTEGER;

BEGIN

i := 0;

WHILE (i < LEN(e)) & (e[i] # 0) DO

StdLog.Int(e[i]);

INC(i)

END;

StdLog.Ln

END Show;

PROCEDURE GenPascalTriangleFor*(p: LONGINT): Expansion;

VAR

expA,expB: Expansion;

i,j: LONGINT;

PROCEDURE Swap(VAR x,y: Expansion);

VAR

swap: Expansion;

BEGIN

swap := x; x := y; y := swap

END Swap;

BEGIN

ASSERT(p > 0);

DEC(p); (* adjust p to work with arrays starting at 0 index *)

NEW(expA,p + 2);NEW(expB,p + 2);

FOR i := 0 TO p DO

IF i = 0 THEN expA[0] := 1

ELSE

FOR j := 0 TO i DO

IF j = 0 THEN

expB[j] := expA[j]

ELSE

expB[j] := expA[j - 1] + expA[j]

END

END;

Swap(expA,expB)

END;

END;

expB := NIL; (* for the GC *)

RETURN expA

END GenPascalTriangleFor;

PROCEDURE Do*;

VAR

s: TextMappers.Scanner;

exp: Expansion;

BEGIN

s.ConnectTo(DevCommanders.par.text);

s.SetPos(DevCommanders.par.beg);

s.Scan;

WHILE (~s.rider.eot) DO

IF (s.type = TextMappers.char) & (s.char = '~') THEN

RETURN

ELSIF (s.type = TextMappers.int) THEN

exp := GenPascalTriangleFor(s.int);

Show(exp)

END;

s.Scan

END

END Do;

END PascalTriangle.

</lang>

<pre>Execute: ^Q PascalTriangle.Do 1 2 3 4 5 6 7 8 9 10 11 12~</pre>

{{out}}

<pre>

1

1 1

1 2 1

1 3 3 1

1 4 6 4 1

1 5 10 10 5 1

1 6 15 20 15 6 1

1 7 21 35 35 21 7 1

1 8 28 56 70 56 28 8 1

1 9 36 84 126 126 84 36 9 1

1 10 45 120 210 252 210 120 45 10 1

1 11 55 165 330 462 462 330 165 55 11 1

</pre>