/C++/Prime numbers less than a given number c++

Prime numbers less than a given number c++

// This Function returns a vector containing all primes less than n using seive of eratosthenes
vector<long long> primes_less_than(long long n)
{
    vector<long long> ans(0);
    if (n <= 2)
        return ans;
    map<long long, bool> is_prime;
    for(long long i=0; i < n; i++) 
      	is_prime[i] = true;
    is_prime[0] = false;
    is_prime[1] = false;

    for (long long i = 2; i < sqrt(n); i++)
        if (is_prime[i])
            for (long long j = i * i; j < n; j += i)
                is_prime[j] = false;

    for(long long i=0; i < n; i++)
      	if (is_prime[i] == true) 
          	ans.push_back(i);
    return ans;
}

Similar codes

0 vote190 views2 answers
QVariant to int
C++
0 vote196 views1 answer
MPI_Sendrecv
C++
0 vote206 views1 answer
Vector keyword in c++
C++
4 votes169 views1 answer
C++ array vs vector
C++
102 votes515 views6 answers
Convert integer to string in c++
C++
0 vote182 views1 answer
Is there garbage collection in c++
C++
0 vote210 views1 answer
Cuda copy memory
C++
21 votes229 views5 answers
Print in c++
C++
9 votes265 views2 answers
Fast io
C++
0 vote189 views1 answer
C++ get type name of object
C++