投稿者: admin_wp

#include <iostream>
#include <chrono>
#include <cmath>
#include <vector>

int main(){

int sqt;
bool flag;
std::vector vec{};

std::chrono::system_clock::time_point  start, end;
start = std::chrono::system_clock::now();

for (int i = 2; i <= 1000000; ++i){         // check prime numbers
    flag = false;
    sqt = sqrt(i);
    for (int j = 2; j <= sqt; ++j){
        if (i%j == 0){
            flag = true;
            break;
        }
    } 
    if (flag != true){
        vec.push_back(i);
    }
}

end = std::chrono::system_clock::now();
double elapsed = std::chrono::duration_cast(end-start).count();
std::cout << "elapsed time : " << elapsed << " ms" << std::endl;

std::cout << std::endl;
std::cout << "number of prime integers(up to 1M) : " << vec.size() << std::endl;
std::cout << std::endl;
std::cout << "last five prime integers " << std::endl;

for (auto itr = (vec.end() - 5); itr != vec.end(); ++itr){
    std::cout << *itr << std::endl;
}
}

import time
import math

start = time.time()
set = list()

flag = False
sqt = 0;
for i in range(2, 1000001):        # check prime numbers
    flag = False;
    sqt = math.sqrt(i)
    for j in range(2, int(sqt) + 1):
        if i%j == 0:
            flag = True
            break
    if flag != True:
        set.append(i)


end = time.time()
print("elapsed time : ",'{:.0f}'.format((end-start)*1000)+ " ms")
print("number of prime integers(up to 1M) : ",len(set))
print("")
print("last five prime integers")
for i in range(5):
    print(set[-5 + i])

c++

elapsed time : 268 ms

number of prime integers(up to 1M) : 78498

last five prime integers 
999953
999959
999961
999979
999983


Python

elapsed time :  9433 ms
number of prime integers(up to 1M) :  78498

last five prime integers
999953
999959
999961
999979
999983