GFG SIEVE OF ERATHOSTHENES

#include <bits/stdc++.h>

using namespace std;
 
void SieveOfEratosthenes(int n) {
    bool prime[n + 1];
    memset(prime, true, sizeof(prime));
 
    for (int p = 2; p * p <= n; p++) {
        if (prime[p] == true) {
            for (int i = p * p; i <= n; i += p)
                prime[i] = false;
        }
    }

    for (int p = 2; p <= n; p++)
        if (prime[p])
            cout << p << " ";
}

int main() {
    int n = 30;
    cout << "Following are the prime numbers smaller " << " than or equal to " << n << endl;
    SieveOfEratosthenes(n);
    return 0;
}