CPP

sieve of eratosthenes c++

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;
    }
}

c++ sieve of eratosthenes

#include <iostream>
#include <vector>
#include <algorithm>
#include <bitset>

#define N 1000000	//N is the Range (0..N)

bitset < N+1 > numbers;
vector < int > primes;

void sieve(){
    numbers.set();
    numbers[1] = 0;

    for (int i = 2; i < N; i++){
        if (numbers[i] == 1){
            cout<<i<<endl;
            primes.push_back(i);
            for (int j = i*i; j<=N; j+=i)
                numbers[j] = 0;
        }
    }
}

Sieve of Eratosthenes c++

    #include <cmath>
    #include <vector>
	using namespace std;
	int n;
    vector<int> ans;
    vector<bool> is_prime(n+1, true);
    is_prime[0] = is_prime[1] = false;
    for (int i = 2; i <= sqrt(n); i++) {
        if (is_prime[i]) {
            for (int j = i * i; j <= n; j += i)
                is_prime[j] = false;
        }
    }
    for(int i=2;i<is_prime.size();i++){
        if(is_prime[i]){
            ans.push_back(i);
        }
    }

sieve of eratosthenes c++

int n;
vector<char> 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;
    }
}