21:素数回文数的个数

 1 #include<iostream>
 2 #include<cmath>
 3 #include<algorithm>
 4 using namespace std;
 5 int sushu(int x)
 6 {
 7     int i=2;
 8     while(i<sqrt(x)&&x%i!=0)
 9     {
10         i++;
11     }
12     if(i>sqrt(x)&&x!=1)
13     {
14         return 1;
15     }
16     else
17     {
18         return 0;
19     }
20 }
21 int huiwen(int x)
22 {
23     int sum=0;
24     while(x)
25     {
26         sum=sum*10+x%10;
27         x/=10;
28     }
29     return sum;
30 }
31 int main()
32 {
33     int r,t=0;
34     cin>>r;
35     for(int i=11;i<=r;++i)
36     {
37         if(sushu(i)&&huiwen(i)==i)
38             t++;
39     }
40     cout<<t;
41     return 0;
42 }