1124 Raffle for Weibo Followers (20)
1124 Raffle for Weibo Followers (20)(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...
题目大意:微博抽奖,给出一串待抽奖人的名字, 给出第一个抽奖的序号s,给出抽奖序号之间的间隔n, 给出所有待抽奖人的人数m; 输出所有被抽中的人的名字, 如果没有一个人被抽中,输出特定字符串。
如果某一个人第二次被选中,则跳过这个人,继续向下抽奖;
思路:用set类型来保存抽中的姓名,可以有效的筛选以及选中的人
1 #include<iostream> 2 #include<set> 3 using namespace std; 4 int main(){ 5 int m, n, s, i; 6 cin>>m>>n>>s; 7 string person[1000]; 8 set<string> winner; 9 bool flag = true; 10 for(i=0; i<m; i++) cin>>person[i]; 11 for(i=s-1; i<m; i+=n){ 12 if(winner.count(person[i])==0){ 13 flag = false; 14 cout<<person[i]<<endl; 15 winner.insert(person[i]); 16 }else{ 17 while(winner.count(person[i]) && i<m){i++;}; 18 cout<<person[i]<<endl; 19 } 20 } 21 if(flag) cout<<"Keep going..."<<endl; 22 return 0; 23 }