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
题意：
给出n个数字，要求输出第一个只出现一次的数字，如果不存在，输出None.
题解：
用类似打表的方法，统计每个数出现的次数。按输出顺序遍历，当有次数为1的数时，输出，没有就输出None。
AC代码：
#include<iostream>
#include<algorithm>
#include<vector>
#include<queue>
#include<map>
#include<string>
#include<cstring>
using namespace std;
int a[10005];
int shu[100005];
int main()
{
int n;
cin>>n;
memset(a,0,sizeof(a));
for(int i=1;i<=n;i++){
cin>>shu[i];
a[shu[i]]++;
}
int f=0;
for(int i=1;i<=n;i++){
if(a[shu[i]]==1){
cout<<shu[i];
f=1;
break;
}
}
if(!f) cout<<"None";
return 0;
}
原文地址：https://www.cnblogs.com/caiyishuai/p/11438337.html