Code:

{

Definition: Permutation

A permutation is an arrangement of n objects, arranged in groups of size r

without repetition where order is important.

P(n,r) = n! / (n-r)!

Example: Find all two-letter permutations of the letters "ABC"

n = ABC

r = 2

Output: AB AC BA BC CA CB

}

{

Definition: Permutation

Eine Permutation ist eine Anordnung von n Objekten ohne Wiederholung.

Dabei spielt die Reihenfolge der Elemente in den Mengen keine Rolle.

P(n,r) = n! / (n-r)!

Beispiel: Finde alle 2-Buchstaben Kombinationen von "ABC"

n = ABC

r = 2

Ergebnis: AB AC BA BC CA CB

}

{

The following is a console Program:

Choose File, New, Console Application

}

program Permute;

{$APPTYPE CONSOLE}

uses SysUtils;

var

R, Slen: Integer;

procedure P(var A: string; B: string);

var

J: Word;

C, D: string;

begin

{ P(N,N) >> R=Slen }

if Length(B) = SLen - R then

begin

Write(' {' + A + '} '); {Per++}

end

else

for J := 1to Length(B) do

begin

C := B;

D := A + C[J];

Delete(C, J, 1);

P(D, C);

end;

end;

var

Q, S, S2: string;

begin

S := ' ';

S2 := ' ';

while (S <> '') and (S2 <> '') do

begin

Writeln('');

Writeln('');

Write('P(N,R) N=? : ');

ReadLn(S);

SLen := Length(S);

Write('P(N,R) R=? : ');

ReadLn(S2);

if s2 <> ''then R := StrToInt(S2);

Writeln('');

Q := '';

P(Q, S);

end;

end.