1041. Be Unique (20)，1041beunique20

1041. Be Unique (20)，1041beunique20

Being unique is so important to people on Mars that even their lottery is designed in a unique way. The rule of winning is simple: one bets on a number chosen from [1, 10⁴]. The first one who bets on a unique number wins. For example, if there are 7 people betting on 5 31 5 88 67 88 17, then the second one who bets on 31 wins.

Input Specification:

Each input file contains one test case. Each case contains a line which begins with a positive integer N (<=10⁵) and then followed by N bets. The numbers are separated by a space.

Output Specification:

For each test case, print the winning number in a line. If there is no winner, print "None" instead.

7 5 31 5 88 67 88 17

31

5 888 666 666 888 888

None

 1 #include <iostream>
 2 #include <set>
 3 using namespace std;
 4 
 5 int main(){
 6     int n;
 7     int i,t;
 8     cin>>n;
 9     set<int> s,s1;
10     int record[n];
11     cin>>t;
12     s.insert(t);
13     s1.insert(t);
14     record[0] = t;
15     for(i = 1; i < n; i++){
16         cin>>t;
17         record[i] = t;
18         if(s1.find(t) != s1.end() && s.find(t) != s.end()){
19             s.erase(t);
20         }
21         else if(s1.find(t) == s1.end()){
22             s.insert(t);
23             s1.insert(t);
24         }
25 
26     }
27     if(s.empty()){
28         cout<<"None";
29     }else{
30         i = 0;
31         while(s.find(record[i]) == s.end()){
32             i++;
33         }
34         cout<<record[i]<<endl;
35     }
36     return 0;
37 }