Generate Prime Numbers in the 1..x range.
http://leetcode.com/2010/04/finding-prime-numbers.html
/* Generate a prime list from 0 up to n, using The Sieve of Erantosthenes
param n The upper bound of the prime list (including n)
param prime[] An array of truth value whether a number is prime
*/
void prime_sieve(int n, bool prime[]) {
prime[0] = false;
prime[1] = false;
int i;
for (i = 2; i <= n; i++) {
prime[i] = true;
}
int limit = sqrt(n);
for (i = 2; i <= limit; i++) {
if (prime[i]) {
for (int j = i * i; j <= n; j += i)
prime[j] = false;
}
}
}