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  1. #include <stdio.h>
  2. #include <time.h>
  3. #include <math.h>
  4.  
  5. int main(void) {
  6.     int count;
  7. 	int i;
  8. 	int j;
  9. 	int k;
  10. 	int c;
  11. 	int prime;
  12. 	clock_t start;
  13. 	clock_t end;
  14. 	double elapsed;
  15. 	int primes[100];
  16.  
  17. 	/* init primes */
  18. 	primes[0] = 2;
  19. 	c = 1;
  20.  
  21. 	/* input */
  22. 	scanf("%d", &count);
  23.  
  24. 	/* measure time */
  25. 	start = clock();
  26. 	for (i = 3; c < count; i += 2) {
  27. 		/* isPrime */
  28. 		k = sqrt(i);
  29. 		prime = 1;
  30. 		for (j = 0; primes[j] <= k; j++) {
  31. 			if (i % primes[j] == 0) {
  32. 				prime = 0;
  33. 				break;
  34. 			}
  35. 		}
  36. 		if (prime) {
  37. 			primes[c] = i;
  38. 			c = c + 1;
  39. 		}
  40. 	}
  41. 	end = clock();
  42. 	elapsed = end - start;
  43.  
  44. 	/* output */
  45. 	for (i = 0; i < count; i++) {
  46. 		printf("%d ", primes[i]);
  47. 	}
  48. 	printf("\n");
  49. 	printf("elapsed time:%f\n", elapsed); 
  50.  
  51. 	return 0;
  52. }
Success #stdin #stdout 0.02s 1724KB
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stdin
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stdout
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2 3 5 7 11 13 17 19 23 29 
elapsed time:0.000000
https://ideone.com/AClvxE
language:
C (gcc 8.3)
created:
11 years ago
visibility:
public

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