32 lines
863 B
C
32 lines
863 B
C
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//
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// Tomás Oliveira e Silva, AED, October 2021
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//
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// This program implements a simple sieve of Eratosthenes.
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// It does not work as intended. Use the valgrind and
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// gdb programs to find the programming errors. Correct them.
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//
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#include <stdio.h>
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#include <stdlib.h>
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int main(void) {
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const int limit = 1000000;
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int *sieve = (int *)malloc((size_t)limit);
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if(sieve == NULL)
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return 1;
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for(int i = 0;i <= limit;i++)
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sieve[i] = 0;
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sieve[0] = sieve[1] = 1; // 0 and 1 are not prime
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for(int p = 2;p * p <= limit;p++)
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if(sieve[p] == 0)
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for(int i = p * p;i <= limit;i += p)
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sieve[i] = 1; // i is not prime
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int c = 0;
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for(int i = 0;i <= limit;i++)
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if(sieve[i] == 0)
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c++;
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printf("There are %d prime numbers up to %d\n",c,limit);
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free(sieve);
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return 0;
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}
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