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  1. #include <stdio.h>
  2.  
  3. #define COG1_TEETH    4
  4. #define COG2_TEETH    25
  5. #define COG3_TEETH    4
  6. #define BASE (4 * COG1_TEETH * COG2_TEETH * COG3_TEETH - 16)
  7.  
  8. int isleap(int year);
  9.  
  10. int main(void)
  11. {
  12. 	int year = 2100;
  13.  
  14. 	printf("%d is %s\n", year, isleap(year) ? "a leap year" : "not a leap year");
  15.  
  16.     return 0;
  17. }
  18.  
  19. int isleap(int year)
  20. {
  21.     unsigned a, b, c;
  22.     unsigned i;
  23.  
  24.     if (year < BASE) return 0;      /* Not Gregorian year */
  25.  
  26.     a = 0;
  27.     b = COG2_TEETH - COG1_TEETH;
  28.     c = COG3_TEETH - 1;
  29.     i = year - BASE;
  30.  
  31.     while (i--) {
  32.         if (++a == COG1_TEETH) {
  33.             a = 0;
  34.             if (++b == COG2_TEETH) {
  35.                 b = 0;
  36.                 if (++c == COG3_TEETH)
  37.                     c = 0;
  38.             }
  39.         }
  40.     }
  41.  
  42.     return !b ? !a && !c : a == 0;
  43. }
  44.  
Success #stdin #stdout 0s 5244KB
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Standard input is empty
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2100 is not a leap year
https://ideone.com/joH9bi
language:
C (gcc 8.3)
created:
41 days ago
visibility:
secret

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