问题 C: Be Unique (20)（哈希）

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 Copy

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

样例输出 Copy

31
None

#include<bits/stdc++.h>
using namespace std;
/* run this program using the console pauser or add your own getch, system("pause") or input loop */
int main(int argc, char** argv) {
	int n;
	int hash_map[10005] = {0};
	while(cin >> n){
		int a[n];
		for(int i = 0; i < n; i++){
			cin >> a[i];
			hash_map[a[i]]++;
		}
		int i;
		for(i = 0; i < n; i++){
			if(hash_map[a[i]] == 1){
				cout << a[i] << endl;
				break;
			}
		}
		if(i == n) cout << "None" << endl;
	}
	return 0;
}