标签:prime temp 23 int system Reversible 1015 Primes Yes
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 (<) and D (1), 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
题意:
给出一个十进制数字N,将这个数字用D进制表示并反转后,问这个数字还是不是素数。
思路:
字符串 + 模拟。
Code:
1 #include <bits/stdc++.h> 2 3 using namespace std; 4 5 bool isPrime(int n) { 6 if (n == 1) return false; 7 for (int i = 2; i * i <= n; ++i) { 8 if (n % i == 0) { 9 return false; 10 } 11 } 12 return true; 13 } 14 15 int main() { 16 int n, d; 17 cin >> n; 18 while (n > 0) { 19 cin >> d; 20 string temp = ""; 21 int r = n; 22 while (r > 0) { 23 temp += to_string(r % d); 24 r /= d; 25 } 26 int index = 0; 27 for (int i = temp.size() - 1; i >= 0; --i) 28 r += (temp[i] - '0') * pow(d, index++); 29 if (isPrime(n) && isPrime(r)) { 30 cout << "Yes" << endl; 31 } else { 32 cout << "No" << endl; 33 } 34 cin >> n; 35 } 36 37 return 0; 38 }
标签:prime,temp,23,int,system,Reversible,1015,Primes,Yes 来源: https://www.cnblogs.com/ruruozhenhao/p/13188951.html
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