//Written by Coffee. 判断素数
bool isPrime(int num)
{
if (num == 2 || num == 3)
return true;
if (num % 6 != 1 && num % 6 != 5)
return false;
for (int i = 5; i*i <= num; i += 6){
if (num % i == 0 || num % (i+2) == 0)
return false;
}
return true;
}
(我觉得有必要整理一下模板了,,)