Source code in the xpl0 programming language

include xpllib; \for Print

char Deck(52), BlackPile(52), RedPile(52), DiscardPile(52),
     BlackBunch(52),  RedBunch(52);
int  I, J, T, M, X, Y, BP, RP, DP, BB, RB, BC, RC;

proc Show;
[Print("Black pile:     ");
for I:= 0 to BP-1 do ChOut(0, BlackPile(I));
Print("\nRed pile:       ");
for I:= 0 to RP-1 do ChOut(0, RedPile(I));
Print("\nDiscard pile:   ");
for I:= 0 to DP-1 do ChOut(0, DiscardPile(I));
Print("\n");
];

[for I:= 0 to 26-1 do
    [Deck(I):= ^r;  Deck(I+26):= ^b];
for I:= 0 to 52-1 do
    [Y:= Ran(52);       \0..51
    T:= Deck(I);  Deck(I):= Deck(Y);  Deck(Y):= T;
    ];
BP:= 0;  RP:= 0;  DP:= 0;
for I:= 0 to 52-1 do
    [if Deck(I) = ^b then
        [BlackPile(BP):= Deck(I+1);  BP:= BP+1]
    else
        [RedPile  (RP):= Deck(I+1);  RP:= RP+1];
    DiscardPile(DP):= Deck(I);  DP:= DP+1;
    I:= I+1;
    ];
Show;
M:= BP;
if RP < M then M:= RP;
X:= Ran(M) + 1;
Print("Swap %d cards between the red and black piles.\n", X);
RB:= 0;  BB:= 0;
for I:= 0 to X-1 do
    [repeat Y:= Ran(RP);  until RedPile(Y) # 0;
    RedBunch(RB):= RedPile(Y);  RB:= RB+1;  RedPile(Y):= 0;
    ];
for I:= 0 to X-1 do
    [repeat Y:= Ran(BP);  until BlackPile(Y) # 0;
    BlackBunch(BB):= BlackPile(Y);  BB:= BB+1;  BlackPile(Y):= 0;
    ];
RB:= 0;
for I:= 0 to X-1 do
    [J:= 0;
    while BlackPile(J) # 0 do J:= J+1;
    BlackPile(J):= RedBunch(RB);  RB:= RB+1;
    ];
BB:= 0;
for I:= 0 to X-1 do
    [J:= 0;
    while RedPile(J) # 0 do J:= J+1;
    RedPile(J):= BlackBunch(BB);  BB:= BB+1;
    ];
Show;
BC:= 0;
for I:= 0 to BP-1 do
    if BlackPile(I) = ^b then BC:= BC+1;
RC:= 0;
for I:= 0 to RP-1 do
    if RedPile(I) = ^r then RC:= RC+1;
Print("The number of black cards in the black pile is %d.\n", BC);
Print("The number of red   cards in the red   pile is %d.\n", RC);
Print("The mathematician's assertion is%s correct.\n",
    if BC#RC then " not" else "");
]