6112 ：Be Unique (20)

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问题 C: Be Unique (20)

时间限制: 1 Sec 内存限制: 32 MB
提交: 279 解决: 137
[提交][状态][讨论版][命题人:外部导入]

题目描述

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.

输入

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.

输出

For each test case, print the winning number in a line. If there is no winner, print "None" instead.

样例输入

7 5 31 5 88 67 88 17
5 888 666 666 888 888

样例输出

31
None

#include<iostream>
#include<map>
//此题手写哈希很方便，不需要map等容器,用map反而更慢,PAT1041中此法有一个数据超时
//unordered_map只去重不排序,但每次使用都将键值放在最前,排序会混乱
using namespace std;
int b[100500];
int main() {
	int n;
	while (cin >> n) {
		map<int, int> a;
		for (int i = 0; i < n; i++) {
			cin >> b[i];
			a[b[i]]++;
		}
		for (int i = 0; i < n; i++) {
			if (a[b[i]] == 1) {
				cout << b[i] << endl;
				break;
			}
			if (i == n - 1)
				cout << "None" << endl;
		}
	}
	return 0;
}