Sieve of Eratosthenes

vector<bool> primes(100001, true);//global array

// Time complexity :- n(log(log((n)^1/2)))+O(n)
void sieve()
{

    int n = 10000;

    primes[0] = primes[1] = false; // 0 and 1 are not prime so primes is false;

    for (int i = 2; i <= n; i++)
    {
        if (primes[i] == true)
        {
            for (int j = i * i; j <= n; j += i)
            {
                primes[j] = false;
            }
        }
    }

    // primes array which has value true are primes

    for (int i = 1; i <= n; i++)
        if (primes[i])
            cout << i << " ";
}