/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 vote103 views1 answer
Identity
C++
7 votes141 views1 answer
How to check string contains char in c++
C++
3 votes92 views1 answer
(a) one-dimensional arrays and multidimensional arrays in c++
C++
1 vote318 views1 answer
How to iterater map of sets in c++
C++
0 vote169 views1 answer
How to format decimal palces in c++
C++
0 vote126 views1 answer
Binary multiplication
C++
6 votes127 views6 answers
Ue4 log
C++
0 vote143 views1 answer
I++ and++i
C++
3 votes144 views1 answer
Reference function in c++
C++
21 votes200 views3 answers
C++ access second last element of vector
C++