https://pintia.cn/problem-sets/994805342720868352/problems/994805444361437184

1041 Be Unique (20)（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 <cstring>
using namespace std; 
const int nmax=1e4+10;
const int nmaxx=1e5+10;
int num[nmaxx];
int hashtable[nmax];
int main(int argc, char** argv) {
	int n;
	while(cin>>n){
		//int num[n];
		//int hashtable[nmax];
		memset(num,0,sizeof(num));
		memset(hashtable,0,sizeof(hashtable));
		for(int i=0;i<n;i++){
			cin>>num[i];
			hashtable[num[i]]++;
		}
		int flag=0;
		for(int i=0;i<n;i++){
			if(hashtable[num[i]]==1){
				cout<<num[i]<<endl;
				flag=1;
				break;
			}
		}
		if(!flag){
		   cout<<"None"<<endl; 
		} 
	} 
	return 0;
}