Add sieve of eratosthenes

problem-357.c

@@ -1,6 +1,7 @@
 #include <math.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include "primes.h"
 
 #define	MAX_NUM	100000000
@@ -13,6 +14,7 @@ int main(int argc, char **argv)
 	long sum = 0;
 	char *primes;
 
+	/*
 	primes = malloc((MAX_NUM+1)*sizeof(char));
 	for (i=1; i<MAX_NUM+1; i++) {
 		if (is_prime(i)) {
@@ -21,6 +23,12 @@ int main(int argc, char **argv)
 			primes[i] = FALSE;
 		}
 	}
+	*/
+	primes = eratosthenes(MAX_NUM);
+	if (primes == NULL) {
+		printf("Error");
+		return 1;
+	}
 
 	for(i=1; i<MAX_NUM; i++) {
 		match = TRUE;