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  1. #include <time.h>
  2. #include <stdlib.h>
  3. #include <stdio.h>
  4.  
  5.  
  6.  
  7. int rand7(void)
  8. {
  9.     const int ret[][2] = {
  10.         {2, 1}, {3, 2}, {5, 3}, {6, 4}, {8, 5}, {10, 6}, {12, 7}
  11.     };
  12.     srand((unsigned)time(NULL));
  13.     int a = rand() % 5 + 1;
  14.     int b = rand() % 5 + 1;
  15.     int i;
  16.     for (i = 0; i < 7; i++) {
  17.         if (a*b == ret[i][0]) {
  18.             return ret[i][1];
  19.         }
  20.     }
  21.     return 0;    
  22. }
  23.  
  24. int main(void)
  25. {
  26.     int num = 0;
  27.     while (num == 0) {
  28.         num = rand7();
  29.     }
  30.     printf("%d\n", num);
  31.     return 0;
  32.  
  33. }
Success #stdin #stdout 0.02s 1676KB
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stdout 
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https://ideone.com/U1Vwj
language:
C (gcc 8.3)
created:
11 years ago
visibility:
public

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