Sieve of Eratosthenes

#include <iostream>
using namespace std;

int main()
{
    int n;
    cin >> n;

    bool cut[n + 1]; // list of number from 1 to n that has been discarded (ignore 0 and 1)
    for (int i = 0; i <= n; i++) // initialize false
        cut[i] = false;

    // keep cutting
    int curMin = 2;
    while (curMin <= n)
    {
        // starts cutting from second multiple of it
        // for example, curMin = 2 will cut 4, 6, 8, 10, ...
        for (int i = 2 * curMin; i <= n; i += curMin)
            cut[i] = true;

        // finds next not-yet-cut number (prime number)
        do
        {
            curMin++;
        } while (cut[curMin]);
    }

    // print all non-cut number
    for (int i = 2; i <= n; i++)
    {
        if (!cut[i])
            cout << i << endl;
    }

    return 0;
}