output.txt

primality test using primality_sqrt_bound_coprime_2(int64_t)
L = 100000000 : R = 100100000
test 1 duration : 0.418 s
test 2 duration : 0.393 s
test 3 duration : 0.397 s
test 4 duration : 0.406 s
test 5 duration : 0.379 s
test 6 duration : 0.381 s
test 7 duration : 0.383 s
test 8 duration : 0.383 s
test 9 duration : 0.376 s
test 10 duration : 0.38 s
average of 10 test(s) : 0.3896 s

primality_sqrt_bound_coprime_2.cpp

#include <cmath>

bool primality_sqrt_bound_coprime_2(int64_t a) {
    if(a % 2 == 0) return a == 2;
    double lim = sqrt(a);
    for(int i = 3; i <= lim; i += 2)
        if(a % i == 0)
            return false;
    return true;
}