A1041 Be Unique

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,]. 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

#include <iostream>
#include <cstdio>
#include <string>
#include <algorithm>
using namespace std;

int hashtable[10001] = {0};

int main()
{
	int n, ans = -1;
	scanf("%d", &n);
	int a[n];
	for(int i=0; i<n; i++){
		scanf("%d", &a[i]);
		hashtable[a[i]]++;
	}
	for(int i=0; i<n; i++){
		if(hashtable[a[i]] == 1){
			ans = a[i]; 
			break;
		}
	}
	if(ans == -1) printf("None");
	else printf("%d\n", ans);
	return 0;
}