//cow02.c  -- by tsaiwn@csie.nctu.edu.tw
//sample to generate ALL possible answers for Bll&Cow game
#include<stdio.h>
int x[5040];
/* 總共 0123 到 9876 四位數不同者有 5040 個 = 10*9*8*7 */
int prepare();   /* 填滿 0123 .. 9876 into x[] */
void next(int);  /* 印 "," 或是 "\n" */
    /***********/
int main(){
   int i, n;
   static char tmpbuf[99];   /* temporary buffer */
   fprintf(stderr, " to generate ALL possible answers for B&C game.\n");
   n = prepare();
   printf("Total %d numbers found. ", n);
   printf("The first 80 numbers:\n");
   for(i=0; i< 80; i++, next(i))
      printf(" %04d", x[i]);
   printf("\n Hit return to continue...");
   fgets(tmpbuf,99, stdin);  /* wait a line input */
   for(i=80; i< 5040; i++, next(i))
      printf(" %4.4d", x[i]);
   printf("\nBye bye\n");
}
void next(int i){
   if(i%8) printf(",");
   else printf("\n");
}
int prepare(){
    int p=0, i,k,m,n;
    for(i=0; i<=9; i++){
        for(k=0; k<=9; k++){
            if(k==i) continue;   /* 第二位k與第一位數i相同的都不要 */
            for(m=0; m<=9; m++){
                if(m==k || m==i) continue;
                for(n=0; n<=9; n++){
                   if(n==m || n==k || n==i) continue;
                   x[p++] = i*1000+k*100+m*10+n;
                }
            }
        }
    }
    return p;
}