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  1. #include <stdlib.h>
  2. #include <stdio.h>
  3.  
  4.  
  5.  
  6.  
  7.  
  8. int main() {
  9. 	int N = 0, i = 0, k = 0, count = 0, stack = 0;
  10. 	do {
  11. 		scanf("%d", &N);
  12. 		if (N == 0) return 0;
  13. 		else {
  14. 			int* arr = (int*)malloc(sizeof(int) * (2 * N + 2));
  15. 			for (i = 0; i < 2 * N; i++) {
  16. 				arr[i] = 1;
  17. 			}
  18. 			arr[0] = 0;
  19. 			for (i = 2; i * i <= 2 * N; i++) {
  20. 				if (arr[i-1] == 1) {
  21. 					for (k = i * 2; k <= 2*N; k += i)
  22. 						arr[k-1] = 0;
  23. 				}
  24. 			}
  25. 			for (i = N; i < 2 * N; i++) {
  26. 				if (arr[i] == 1)
  27. 					count++;
  28. 			}
  29. 			free(arr);
  30. 			printf("%d", count);
  31. 			count = 0;
  32. 		}
  33.  
  34. 	} while (N != 0);
  35. }
Success #stdin #stdout 0s 9424KB
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1432113510338392
https://ideone.com/ZHzE3p
language:
C (gcc 8.3)
created:
4 years ago
visibility:
public

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