pat 1124 Raffle for Weibo Followers（20 分）

1124 Raffle for Weibo Followers（20 分）

John got a full mark on PAT. He was so happy that he decided to hold a raffle（抽奖） for his followers on Weibo -- that is, he would select winners from every N followers who forwarded his post, and give away gifts. Now you are supposed to help him generate the list of winners.

Input Specification:

Each input file contains one test case. For each case, the first line gives three positive integers M (≤ 1000), N and S, being the total number of forwards, the skip number of winners, and the index of the first winner (the indices start from 1). Then M lines follow, each gives the nickname (a nonempty string of no more than 20 characters, with no white space or return) of a follower who has forwarded John's post.

Note: it is possible that someone would forward more than once, but no one can win more than once. Hence if the current candidate of a winner has won before, we must skip him/her and consider the next one.

Output Specification:

For each case, print the list of winners in the same order as in the input, each nickname occupies a line. If there is no winner yet, print Keep going... instead.

Sample Input 1:

9 3 2
Imgonnawin!
PickMe
PickMeMeMeee
LookHere
Imgonnawin!
TryAgainAgain
TryAgainAgain
Imgonnawin!
TryAgainAgain

Sample Output 1:

PickMe
Imgonnawin!
TryAgainAgain

Sample Input 2:

2 3 5
Imgonnawin!
PickMe

Sample Output 2:

Keep going...

 #include <iostream>
 #include <algorithm>
 #include <cstdio>
 #include <cstring>
 #include <map>
 #include <stack>
 #include <vector>
 #include <queue>
 #include <set>
 using namespace std;
 const int MAX = 1e3 + ;

 int m, n, s, cnt = ;
 struct node
 {
     char s[];
 }P[MAX], S[MAX];
 set <string> st;
 pair <set <string> :: iterator, bool> pr;
 set <string> :: iterator iter;

 int main()
 {
 //    freopen("Date1.txt", "r", stdin);
     scanf("%d%d%d", &m, &n, &s);
     for (int i = ; i <= m; ++ i)
         scanf("%s", &P[i].s);

     for (int i = s; i <= m; i += n)
     {
         pr = st.insert(P[i].s);
         if (pr.second)
         {
             strcpy(S[cnt ++].s, P[i].s);
             continue;
         }
         while (i <= m)
         {
             ++ i;
             pr = st.insert(P[i].s);
             if (pr.second)
             {
                 strcpy(S[cnt ++].s, P[i].s);
                 break;
             }
         }
     }

     if (cnt == )
     {
         printf("Keep going...\n");
         return ;
     }
     for (int i = ; i < cnt; ++ i)
         printf("%s\n", S[i].s);
     return ;
 }