PAT Grade --A1041 Be Unique

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]. 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 (≤) 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 <unordered_map>
 3 using namespace std;
 4 int N, num[100001];
 5 int main()
 6 {
 7     cin >> N;
 8     unordered_map<int, int> numbers;
 9     for (int i = 0; i < N; ++i)
10     {
11         cin >> num[i];
12         numbers[num[i]]++;//In order to ensure that a single order of the number of seats obtained deposit by means NUM [I] 
13 is      }
 14      for ( int I = 0 ; I <N; ++ I)
 15      {
 16          IF (Numbers [NUM [I]] == . 1 )
 . 17          {
 18 is              COUT << NUM [I] << endl;
 . 19              return  0 ;
 20 is          }
 21 is      }
 22 is      COUT << " None " << endl;
 23 is      return  0 ;
 24 }