PTA甲级——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

题目大意：给出序列的长度和一个数字序列，输出序列中第一个只出现一次的数字，如果不存在则输出None。

类似于桶排序，可以使用一个数组直接记录每个数字出出现的次数，（如果数字过大，会造成大量的内存浪费，可以使用哈希表），然后顺序遍历序列查找。（如果不想要一个相同的数字被多次和查找，可以使用set来优化）
代码实现：

#include <iostream>
using namespace std;

int times[10005], num[10005]; 

int main()
{
	int t, temp, bit, sign = 0, cnt = 0;

	cin >> t;
	while (t--)
	{
		cin >> temp;
		if (times[temp] == 0) { num[cnt++] = temp; times[temp]++; }
		else times[temp]++;
	}

	for (int i = 0; i < cnt; i++) 
	{ 
		if (times[num[i]] == 1) 
		{ 
			cout << num[i]; 
			sign = 1; 
			break; 
		} 
	}
	if (!sign) cout << "none";
	return 0;
}