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#include <stdbool.h>
#include <pthread.h>
#define NTHREADS 16
bool isprime(int);
void *pthread_routine(void *);
struct interval { int low; int high; int count; };
int primes_in_range(int low, int high) {
pthread_t threads[NTHREADS];
struct interval args[NTHREADS];
if (low < 0 || high < low)
return 0;
int interval_size = (high-low)/NTHREADS + 1;
for (int i = 0; i < NTHREADS; i++) {
args[i].low = low + i*interval_size;
args[i].high = args[i].low + interval_size;
pthread_create(&threads[i], NULL, pthread_routine, &args[i]);
}
int result = 0;
for (int i = 0; i < NTHREADS; i++) {
pthread_join(threads[i], NULL);
result += args[i].count;
}
return result;
}
bool isprime(int n) {
if (n < 2)
return false;
for (int i = 2; i*i <= n; i++)
if (n % i == 0)
return false;
return true;
}
void *pthread_routine(void *arg) {
struct interval *interval = arg;
interval->count = 0;
for (int i = interval->low; i < interval->high; i++)
if (isprime(i))
interval->count++;
return NULL;
}
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