Use an equal probability single draw algorithm to get card from deck.

Patch supplied by John Darrow in PR bin/9651.

diff --git a/fish/fish.c b/fish/fish.c
index 05d73af7cf661f693f0dabcd6528082586515d7e..25c1977e64c23961361c564e16eb85591ba1d5e7 100644 (file)
--- a/fish/fish.c
+++ b/fish/fish.c
@@ -1,4 +1,4 @@
-/*     $NetBSD: fish.c,v 1.11 1999/09/22 18:55:14 jsm Exp $    */
+/*     $NetBSD: fish.c,v 1.12 2000/03/28 19:37:54 tron Exp $   */
 
 /*-
  * Copyright (c) 1990, 1993
@@ -46,7 +46,7 @@ __COPYRIGHT("@(#) Copyright (c) 1990, 1993\n\
 #if 0
 static char sccsid[] = "@(#)fish.c     8.1 (Berkeley) 5/31/93";
 #else
-__RCSID("$NetBSD: fish.c,v 1.11 1999/09/22 18:55:14 jsm Exp $");
+__RCSID("$NetBSD: fish.c,v 1.12 2000/03/28 19:37:54 tron Exp $");
 #endif
 #endif /* not lint */
 
@@ -65,6 +65,7 @@ __RCSID("$NetBSD: fish.c,v 1.11 1999/09/22 18:55:14 jsm Exp $");
 #define        RANKS           13
 #define        HANDSIZE        7
 #define        CARDS           4
+#define        TOTCARDS        RANKS * CARDS
 
 #define        USER            1
 #define        COMPUTER        0
@@ -77,8 +78,9 @@ const char *const cards[] = {
 #define        PRC(card)       (void)printf(" %s", cards[card])
 
 int promode;
-int asked[RANKS], comphand[RANKS], deck[RANKS];
+int asked[RANKS], comphand[RANKS], deck[TOTCARDS];
 int userasked[RANKS], userhand[RANKS];
+int curcard = TOTCARDS;
 
 void   chkwinner __P((int, const int *));
 int    compmove __P((void));
@@ -170,7 +172,7 @@ usermove()
                        continue;
                if (buf[0] == '\n') {
                        (void)printf("%d cards in my hand, %d in the pool.\n",
-                           countcards(comphand), countcards(deck));
+                           countcards(comphand), curcard);
                        (void)printf("My books:");
                        (void)countbooks(comphand);
                        continue;
@@ -270,9 +272,7 @@ drawcard(player, hand)
 {
        int card;
 
-       while (deck[card = nrandom(RANKS)] == 0);
-       ++hand[card];
-       --deck[card];
+       ++hand[card = deck[--curcard]];
        if (player == USER || hand[card] == CARDS) {
                printplayer(player);
                (void)printf("drew %s", cards[card]);
@@ -423,19 +423,21 @@ countbooks(hand)
 void
 init()
 {
-       int i, rank;
+       int i, j, temp;
 
-       for (i = 0; i < RANKS; ++i)
-               deck[i] = CARDS;
-       for (i = 0; i < HANDSIZE; ++i) {
-               while (!deck[rank = nrandom(RANKS)]);
-               ++userhand[rank];
-               --deck[rank];
+       for (i = 0; i < TOTCARDS; ++i)
+               deck[i] = i % RANKS;
+       for (i = 0; i < TOTCARDS - 1; ++i) {
+               j = nrandom(TOTCARDS-i);
+               if (j == 0)
+                       continue;
+               temp = deck[i];
+               deck[i] = deck[i+j];
+               deck[i+j] = temp;
        }
        for (i = 0; i < HANDSIZE; ++i) {
-               while (!deck[rank = nrandom(RANKS)]);
-               ++comphand[rank];
-               --deck[rank];
+               ++userhand[deck[--curcard]];
+               ++comphand[deck[--curcard]];
        }
 }