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

 1 #include <iostream>
 2 #include <algorithm>
 3 #include <cstdio>
 4 #include <cstring>
 5 #include <map>
 6 #include <stack>
 7 #include <vector>
 8 #include <queue>
 9 #include <set>
10 #define LL long long
11 using namespace std;
12 const int MAX = 1e5 + 10;
13 
14 map <int, int> mp;
15 map <int, int> :: iterator iter;
16 int n, a, A[MAX];
17 
18 int main()
19 {
20 //    freopen("Date1.txt", "r", stdin);
21     scanf("%d", &n);
22     for (int i = 0; i < n; ++ i)
23     {
24         scanf("%d", &a);
25         A[i] = a;
26         mp[a] ++;
27     }
28 
29     for (int i = 0; i < n; ++ i)
30     {
31         if (mp[A[i]] == 1)
32         {
33             printf("%d\n", A[i]);
34             return 0;
35         }
36     }
37     printf("None\n");
38     return 0;
39 }