public static bool[] SieveOfEratosthenes(int num)
{
bool[] isPrime = new bool[num + 1];
for (int i = 2; i <= num; i++) isPrime[i] = true;
// Removing multiples.
for (int i = 2; i <= num; i++)
{
if (isPrime[i])
{
for (int j = i * 2; j <= num; j += i)
isPrime[j] = false; // Eliminate multiples of i.
}
}
return isPrime;
}
function solution(n) {
const numArr = new Array(n + 1);
numArr.fill(true);
numArr[0] = numArr[1] = false;
for (let i = 2; i <= Math.sqrt(n); i++) {
for (let j = 2; i * j <= n; j++) {
numArr[i * j] = false;
}
}
return numArr.filter(Boolean).length;
}
int n;
vector<bool> is_prime(n+1, true);
is_prime[0] = is_prime[1] = false;
for (int i = 2; i <= n; i++) {
if (is_prime[i] && (long long)i * i <= n) {
for (int j = i * i; j <= n; j += i)
is_prime[j] = false;
}
}