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From: "Rod Pemberton" <boo@fasdfrewar.cdm>
Newsgroups: alt.os.development
Subject: Re: cows and bulls game, was [Re: C parser ramblings, language design, etc]
Date: Sun, 27 Dec 2015 21:19:09 -0500
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On Sun, 27 Dec 2015 08:51:24 -0500, James Harris <james.harris.1@gmail.com> wrote:

> It reminds me, however, that when I was at school I tried to come up
> with an algorithm for marking a game that some people call bulls-and-cows.

Since you're reminiscing, here is a "bulls-and-cows" test
harness in C I just whipped up after dinner.  You should be able
to modify it to add in an algorithm of your choice rather
easily.  You need to activate a define for either TEST or USER
or RAND.  USER is set.  I don't have a preprocessor check for
none of them set.  TEST uses hardcoded values.  RAND generates
both the guess and secret.  USER lets the user play.  I left in most
standard C functions for you, except memset() which I implemented
as loops, although it's missing niceties like EXIT_SUCCESS, etc.
I likely would've eliminated isdigit() otherwise.  It'll warn on
some unused variables depending on which define you choose.  Ignore
this.  Although one can implement a division at the end using
either floating point or integer arithmetic, I didn't bother.
Some of the code may look rudimentary, e.g., condition to
break exit while(1) loops, or aligned braces, but I assure
you, that I can just as easily code it the other way around.
If you want, you can rework cows() to call bulls().  Redundant.
Or, rework bulls() to pass scs instead of using a file scope var.


/* Bulls and Cows - test harness .RP */
/* Rod Pemberton - Dec 27 2015 */

#include <stdio.h>
#include <ctype.h> /* isdigit */
#include <stdlib.h> /* rand srand */
#include <time.h> /* time */

#define SC 4
#define DG 10

unsigned char secret[SC+1],guess[SC+1];
unsigned int sec_tab[DG],gue_tab[DG];
int scs;

#if 0
#define TEST
#endif
#if 1
#define USER
#endif
#if 0
#define RAND
#endif
#if !defined(TEST) && !defined(USER) && !defined(RAND)
#error "must define one"
#endif
#if defined(TEST) && defined(USER)
#error "two defined"
#endif
#if defined(USER) && defined(RAND)
#error "two defined"
#endif
#if defined(TEST) && defined(RAND)
#error "two defined"
#endif

#ifdef TEST
#define G1
#define S1
#endif
#ifdef RAND
#define G2
#define S2
#endif
#ifdef USER
#define G3
#define S2
#endif

void do_secret()
{
    int i,r;

#ifdef S1
    secret[0]='4';
    secret[1]='0';
    secret[2]='5';
    secret[3]='1';
    printf("Secret is %s.\n",secret);
#endif
#ifdef S2
    for(i=0;i<DG;i++) /* memset */
    {
      sec_tab[i]=0;
    }
    i=0;
    while(1)
    {
      r=(rand()>>3)%DG;
      if(!sec_tab[r])
      {
        secret[i]=r+'0';
        sec_tab[r]=1;
        i++;
      }
      if(i==SC)
        break;
    }
#if 0
    printf("Secret is %s.\n",secret);
#endif
#endif
}

void do_guess()
{
    unsigned char c;
    int i,r;

    printf("Enter guess.\n");
#ifdef G1
    guess[0]='1';
    guess[1]='0';
    guess[2]='3';
    guess[3]='4';
#endif
#ifdef G2
    for(i=0;i<DG;i++) /* memset */
    {
      gue_tab[i]=0;
    }
    i=0;
    while(1)
    {
      r=(rand()>>3)%DG;
      if(!gue_tab[r])
      {
        guess[i]=r+'0';
        gue_tab[r]=1;
        i++;
      }
      if(i==SC)
        break;
    }
#endif
#ifdef G3
    i=0;
    while(1)
    {
      c=getchar();
      if(isdigit((int)c))
      {
        guess[i]=c;
        i++;
      }
      if(i==SC)
        break;
    }
#endif
    printf("Guess is %s.\n",guess);
}

void bulls(void)
{
    int i,sts;

    sts=0;
    for(i=0;i<SC;i++)
    {
      if(guess[i]==secret[i])
        sts++;
    }
    printf("%d bulls ",sts);
    if(sts==SC)
      scs=1;
}

void cows(void)
{
    int i,sts;

    sts=0;
    for(i=0;i<DG;i++) /* memset */
    {
      sec_tab[i]=0;
      gue_tab[i]=0;
    }
    for(i=0;i<SC;i++)
    {
      sec_tab[secret[i]-'0']=1;
      gue_tab[guess[i]-'0']=1;
    }
    for(i=0;i<DG;i++)
    {
      if((sec_tab[i])&&(gue_tab[i]))
        sts++;
    }
    for(i=0;i<SC;i++)
    {
      if(guess[i]==secret[i])
        sts--;
    }
    printf("%d cows\n",sts);
}

int main(void)
{
    char q; /* quit */
    int attempts,games;

    secret[SC]='\0';
    guess[SC]='\0';

    games=0;
    attempts=0;
    while(1)
    {
      games++;
      scs=0;
      srand(time(0));
      do_secret();
      while(1)
      {
        attempts++;
        do_guess();
        bulls();
        cows();
        if(scs)
          break;
        printf("Sorry, try again.\n");
#ifdef TEST
        break;
#endif
      };
      printf("Congratulations!\n");
      printf("Again? 'y' or 'n'\n");
      while(1)
      {
        q=getchar();
        if((q=='n')||(q=='N')||(q=='y')||(q=='Y'))
          break;
      }
      if((q=='n')||(q=='N'))
        break;
    }
    printf("attempts/games %d/%d\n",attempts,games);

return(0);
}

/* .RP */


Rod Pemberton

-- 
The idea that sentient beings can be suppressed by a few simple
rules is a farce.  Even so, Isaac Asimov posited such rules for
sentient artificial intelligence.