RUST

find prime numbers with the sieve of Eratosthenes

fn sieve(in_n: u32) -> Vec<u32> {
    let n = in_n as usize;
    let mut a = Vec::new();
    a.resize(n, true);
    for i in 2..(f64::sqrt(n as f64) as usize + 1) {
        if a[i] {
            for j in (i*i..n).step_by(i) {
                a[j] = false;
            }
        }
    }
    return a.iter().enumerate().filter_map(|(i, &t)| {
      if t {Some(i as u32)} else {None}   
    }).collect();
}

fn main() {
    let n = 12;
    println!("List of primes less than {} = {:?} ", n, sieve(n));
}

sieve of eratosthenes - prime number

# Python program to print all
# primes smaller than or equal to
# n using Sieve of Eratosthenes
 
 
def SieveOfEratosthenes(n):
 
    # Create a boolean array
    # "prime[0..n]" and initialize
    #  all entries it as true.
    # A value in prime[i] will
    # finally be false if i is
    # Not a prime, else true.
    prime = [True for i in range(n+1)]
    p = 2
    while (p * p <= n):
 
        # If prime[p] is not
        # changed, then it is a prime
        if (prime[p] == True):
 
            # Update all multiples of p
            for i in range(p * p, n+1, p):
                prime[i] = False
        p += 1
 
    # Print all prime numbers
    for p in range(2, n+1):
        if prime[p]:
            print(p)
 
 
# Driver code
if __name__ == '__main__':
    n = 20
    print("Following are the prime numbers smaller"),
    print("than or equal to", n)
    SieveOfEratosthenes(n)