Superprime Rib

Butchering Farmer John's cows always yields the best prime rib. You can tell prime ribs by looking at the digits lovingly stamped across them, one by one, by FJ and the USDA. Farmer John ensures that a purchaser of his prime ribs gets really prime ribs because when sliced from the right, the numbers on the ribs continue to stay prime right down to the last rib, e.g.:

     7  3  3  1

The set of ribs denoted by 7331 is prime; the three ribs 733 are prime; the two ribs 73 are prime, and, of course, the last rib, 7, is prime. The number 7331 is called a superprime of length 4.

Write a program that accepts a number N 1 <=N<=8 of ribs and prints all the superprimes of that length.

The number 1 (by itself) is not a prime number.

PROGRAM NAME: sprime

INPUT FORMAT

A single line with the number N.

SAMPLE INPUT (file sprime.in)

4

OUTPUT FORMAT

The superprime ribs of length N, printed in ascending order one per line.

SAMPLE OUTPUT (file sprime.out)

2333233923932399293931193137373337393793379759397193733173337393

终于要到头了!!

/*ID: des_jas1PROG: sprimeLANG: C++*/#include <iostream>#include <fstream>#include <string.h>#include <cmath>#include <algorithm>//#define fin cin//#define fout coutusing namespace std;const int MAX=10001,b[9]={0,10,100,1000,10000,100000,1000000,10000000,100000000};int d;bool sprime[MAX];void initial() //先生成10000以内的素数表{int i,j,n;memset(sprime,0,sizeof(sprime));sprime[2]=true;for(i=3;i<MAX;i+=2)sprime[i]=true;n=MAX/3;for(i=3;i<n;i+=2)if(sprime[i])for(j=i*3;j<MAX;j+=i*2)sprime[j]=false;}bool IsPrime(int t){if(t<MAX){if(sprime[t])return true;else return false;}int i,tp;tp=int(sqrt(t));for(i=3;i<=tp;i+=2){if(sprime[i])if(!(t%i))     return false;}return true;}int main() {ofstream fout("sprime.out");        ifstream fin("sprime.in");int i,j,tp;fin>>d;initial();for(i=b[d-1]+1;i<b[d];i+=2){for(j=d-1;j>0;j--){tp=i/b[j];if((tp!=2 && !(tp%2)) || !(IsPrime(tp)))  //判断它是否为偶数,且不是2这个不能漏掉break;}if(j)continue;IsPrime(i);if(IsPrime(i))fout<<i<<endl;}fout.close();fin.close();    return 0;}