1015 Reversible Primes (20 分)_1015 reversible primes (20分)a reversible prime in -优快云博客

本文介绍了一种算法，用于判断一个数是否为特定进制下的可逆素数。可逆素数是指在一个数系统中，该数及其在这个系统中的“反转”数都是素数的情况。文章提供了一个示例代码，通过将输入的整数转换为其指定进制下的反转数，并检查这两个数是否都为素数来实现这一功能。

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1015 Reversible Primes (20 分)
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 (<10
5
) 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

#include <iostream>
#include <cmath>

using namespace std;

int ConvertAndReverse(int Number,int Radix)
{
	int Remainder,Convert = 0;
	while (Number) {
		Remainder = Number % Radix;
		Number /= Radix;
		Convert = Convert * Radix + Remainder;
	}
	return Convert;
}

bool IsPrime(int N)
{
//	if (N == 2 || N ==3 ) return true;
	if (N == 1) return false;
	int i;
	for (i = sqrt(N); i >= 2; --i) {
		if (N % i == 0)
			return false;
	}
	 return true;
}

int main(void)
{
//	freopen("input.txt", "r", stdin);
	int Number, Radix;
	while (true) {
		cin >> Number;
		if (Number < 0) break;
		cin >> Radix;
		if (IsPrime(Number) && IsPrime(ConvertAndReverse(Number, Radix)))
			cout << "Yes" << endl;
		else cout << "No" << endl;
	}

//	fclose(stdin);
	system("pause");
	return 0;
}