pat 1041 Be Unique（20 分）

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 <algorithm>
 #include <cstdio>
 #include <cstring>
 #include <map>
 #include <stack>
 #include <vector>
 #include <queue>
 #include <set>
 #define LL long long
 using namespace std;
 const int MAX = 1e5 + ;

 map <int, int> mp;
 map <int, int> :: iterator iter;
 int n, a, A[MAX];

 int main()
 {
 //    freopen("Date1.txt", "r", stdin);
     scanf("%d", &n);
     for (int i = ; i < n; ++ i)
     {
         scanf("%d", &a);
         A[i] = a;
         mp[a] ++;
     }

     for (int i = ; i < n; ++ i)
     {
         if (mp[A[i]] == )
         {
             printf("%d\n", A[i]);
             return ;
         }
     }
     printf("None\n");
     return ;
 }