题解 | #素数回文#

#include <stdio.h>

long long palind_num(long long n)//生成回文数
{
    long long num = n;
    while(num>9)
    {
        num /= 10;
        n = n*10 + num%10;
    }
    return n;
}

int prime_num(long long n)//判断回文数是否为质数
{
    int i;
    for(i = 2;i<=sqrt(n);i++)
    {
        if(n%i == 0)
            return 0;
    }
    return 1;
}

int main(void) 
{
    long long n = 0;
    scanf("%lld",&n);
  
    long long ret = palind_num(n);
    int i = prime_num(ret);
   
    if(i == 1)
        printf("prime\n");
    else 
        printf("noprime\n");

    return 0;
}