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 ( $\leq 1000), N and S, being the total number of forwards, the skip number of winners, and the index of the first winner (the indices start from 1). Then M lines follow, each gives the nickname (a nonempty string of no more than 20 characters, with no white space or return) of a follower who has forwarded John's post.$

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<bits/stdc++.h>
using namespace std;
const int maxn=1010;
map<string,int> mp;

int main(){
    int m,n,s;
    cin>>m>>n>>s;
    bool flag=false;
    for(int i=1;i<=m;i++){
        string str;
        cin>>str;
        if(mp[str]==1){
            s++;
        }
        if(mp[str]==0&&i==s){
            mp[str]=1;
            cout<<str<<endl;
            flag=true;
            s+=n;
        }
    }
    if(flag==false){
        cout<<"Keep going..."<<endl;
    }
    return 0;
}