pat甲级1041

#include<iostream>
#include<vector>
#include<map>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
#include<queue>
#include<string>
#include<stack>
#include<set>
using namespace std;
int flag[10010];
queue<int> tmpres;
int main()
{
//	freopen("test.txt", "r", stdin);
	int n, tmp, res = -1;
	scanf("%d", &n);
	for (int i = 0; i < n; ++i)
	{
		scanf("%d", &tmp);
		if (flag[tmp] == 0) {
			flag[tmp]++;
			if(res!=-1)
				tmpres.push(tmp);
			else res = tmp;
		}
		else {
			flag[tmp]++;
			while (!tmpres.empty()&&flag[tmpres.front()] > 1)tmpres.pop();
			if (res == tmp) {
				if (!tmpres.empty())
				{
					res = tmpres.front();
					tmpres.pop();
				}
				else {
					res = -1;
				}
			}
		}
	}
	if (res == -1)cout << "None";
	else cout << res;
	return 0;
}

题目很简答，只是我觉得这是我这几天以来写的最漂亮的代码了，所以放上来自我安慰