PAT 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, 104]. 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 (<=105) 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

这题也比较简单

#include<iostream>
using namespace std;
int a[100001]={0},checked[100001]={0};
int main(){
	int n;
	cin>>n;
	for(int i=0;i<n;i++){
		cin>>a[i];
	    checked[a[i]]++;
	}
	for(int i=0;i<n;i++)
	    if(checked[a[i]]==1){
	       cout<<a[i]<<endl;
	       return 0;
		}
	cout<<"None"<<endl;
	return 0;
}