标签：finish radix pre pac sam its not inpu focus
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.
73 10 23 2 23 10 -2
Sample Output:
Yes Yes No
1 #include <bits/stdc++.h> 2 using namespace std; 3 int n , d; 4 static const int MAXN = 1e5 + 10; 5 bool is_prime[MAXN]; 6 int prime[MAXN]; 7 int pos = 0; 8 void Prime() 9 { 10 for(int i = 2 ; i < MAXN ; ++i) 11 is_prime[i] = 1; 12 for(int i = 2 ; i < MAXN ; ++i) 13 { 14 if(is_prime[i]) 15 prime[++pos] = i; 16 for(int j = 1 ; j <= pos ; ++j) 17 { 18 if(i * prime[j] >= MAXN) 19 break; 20 is_prime[i * prime[j]] = 0; 21 if(i % prime[j] == 0) 22 break; 23 } 24 } 25 } 26 int Reverse() 27 { 28 int sum = 0; 29 do 30 { 31 sum = sum * d + n % d; 32 n /= d; 33 }while(n != 0); 34 return sum; 35 } 36 int main() 37 { 38 Prime(); 39 while(~scanf("%d" , &n)) 40 { 41 if(n < 0) 42 return 0; 43 scanf("%d" , &d); 44 if(is_prime[n] && is_prime[Reverse()]) 45 puts("Yes"); 46 else 47 puts("No"); 48 } 49 }
1015. Reversible Primes (20)(数论:素数、进制转换)
标签：finish radix pre pac sam its not inpu focus
原文地址：http://www.cnblogs.com/jianglingxin/p/6850707.html
