POJ 1317

 1 #include <iostream>
 2 #include <string>
 3 using namespace std;
 4 
 5 char p_code[] = {‘_‘,‘a‘,‘b‘,‘c‘,‘d‘,‘e‘,‘f‘,‘g‘,‘h‘,‘i‘,‘j‘,‘k‘,‘l‘,‘m‘,‘n‘,‘o‘,‘p‘,‘q‘,‘r‘,‘s‘,‘t‘,‘u‘,‘v‘,‘w‘,‘x‘,‘y‘,‘z‘,‘.‘};
 6 int c_code[100];
 7 int ans[100];
 8 
 9 int main()
10 {
11     //freopen("acm.acm","r",stdin);
12     int k;
13     int n;
14     int i;
15     string s;
16     
17     while(cin>>k,k)
18     {
19         cin>>s;
20         n = s.length();
21         for(i = 0; i < n; ++ i)
22         {
23             if(s[i] >= ‘a‘ && s[i] <= ‘z‘)
24             {
25                 c_code[i] = (s.at(i)-‘a‘);
26                 ans[(k*i)%n] = (c_code[i]+1)%28+i;
27             }
28             else if(s[i] == ‘_‘)
29             {
30                 ans[(k*i)%n] = (0+i);
31             }
32             else if(s[i] == ‘.‘)
33             {
34                 ans[(k*i)%n] = (27+i);
35             }
36         }
37         for(i = 0; i < n; ++ i)
38         {
39             cout<<p_code[ans[i]%28];    
40         }
41         cout<<endl;
42         
43     }
44 }