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problem 10 done, and problem 7 rewritten (new is_prime algorithm)

This commit is contained in:
Henrik Hautakoski 2010-04-09 16:20:42 +02:00
parent 8498165fef
commit 2ba8a8aaeb
4 changed files with 64 additions and 36 deletions

47
p7.c
View file

@ -5,50 +5,25 @@
* Projecteuler - Problem 7
* ------------------------
* 2009-12-28 Henrik Hautakoski
*
* fast and elegant solution using The fundamental theorem of arithmetic wich state:
* any natural number greater than 1 can be prime factorized in only one unique way
* unless it is prime itself.
*/
#include <stdio.h>
#include <malloc.h>
int isprime(int *pl, int l, int p) {
int i;
for(i=0; i < l; i++) {
if((p % pl[i]) == 0)
return 0;
}
return 1;
}
#include "lib/prime.h"
int main() {
int i, len = 3, *prime = malloc(sizeof(int)*10001);
uint32_t i, p, n = 1;
if (prime == NULL)
return 1;
prime[0] = 2;
prime[1] = 3;
prime[2] = 5;
for(i=6; len < 10001; i++) {
if(!isprime(prime, len, i))
continue;
prime[len++] = i;
}
for(i=3; n < 10001; i+=2) {
printf("%i\n", prime[len-1]);
free(prime);
if (!is_prime(i))
continue;
p = i;
n++;
}
printf("%i\n", p);
return 0;
}