A1041

1041 Be Unique (20分)

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 [1,10 ​4 ​​ ]. 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 (≤10 ​5 ​​ ) 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.

Sample Input 1:

7 5 31 5 88 67 88 17

Sample Output 1:

31

Sample Input 2:

5 888 666 666 888 888

Sample Output 2:

None

#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<queue>
#include<cstdio>
#include<algorithm>
using namespace std;

int main(){
    int N,a[100005],mp[100005];
    cin>>N;
    for(int i=0;i<N;i++){
        scanf("%d",&a[i]);
        mp[a[i]]++;
    }
    for(int i=0;i<N;i++){
        if(mp[a[i]]==1){
            cout<<a[i]<<endl;
            return 0;
        }
    }
    cout<<"None"<<endl;
    return 0;
}