PAT甲级——1041 Be Unique

1041 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 [1,10​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>
using namespace std;

int main(void)
{
int a[100001] = {0};
int b[100001] = {0};//用来区别该数字是否重复出现
int n,flag=0;
cin >> n;
for (int i = 0; i < n; i++)
{
cin >> a[i];
b[a[i]]++;
}
for (int i = 0; i < n; i++)
{
if (b[a[i]] == 1)
{
cout << a[i] << endl;
return 0;
}
}
if (flag == 0)
cout << "None" << endl;
return 0;
}