【PAT】【Advanced Level】1015. Reversible Primes (20)

1015. Reversible Primes (20)

时间限制

400 ms

内存限制

65536 kB

代码长度限制

16000 B

判题程序

Standard

作者

CHEN, Yue

A reversible prime in any number system is a prime whose "reverse" in that number system is also a prime. For example in the decimal system 73 is a reversible prime because its reverse 37 is also a prime.

Now given any two positive integers N (< 10⁵) and D (1 < D <= 10), you are supposed to tell if N is a reversible prime with radix D.

Input Specification:

The input file consists of several test cases. Each case occupies a line which contains two integers N and D. The input is finished by a negative N.

Output Specification:

For each test case, print in one line "Yes" if N is a reversible prime with radix D, or "No" if not.

Sample Input:

73 10
23 2
23 10
-2

Sample Output:

Yes
Yes
No

原题链接：

https://www.patest.cn/contests/pat-a-practise/1015

思路：

按要求分解、翻转、模拟

坑点：

不要忘记判断原数是否为0

CODE：

#include
using namespace std;
bool pri(int n)
{
    if (n==0 || n==1) return false;
    for (int i=2;i*i<=n;i++)
    {
        if (n%i==0) return false;
    }
    return true;
}
int rev(int n,int ra)
{
    string re="";
    while (n!=0)
    {
        re+=('0'+n%ra);
        n/=ra;
    }
    int rev=0;
    for (int i=0;i>n;
    while (n>=0)
    {
        cin>>ra;
        if (pri(n)==0)
        {
            cout<<"No"<>n;
    }
    return 0;
}