1041 Be Unique (20 分) 简单hash

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 [1,104]. 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.

Input Specification:

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.

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

#include<bits/stdc++.h>
using namespace std;
const int maxn=100010;
int main(){
  //freopen("in.txt","r",stdin);
  int a[maxn],hash[maxn]={0};
  int N,n,num;
  cin>>N;
  while(N--){
    cin>>n;
    if(hash[n]==0) a[num++]=n;
    hash[n]++;
  }
  int i;
  for(i=0;i<num;i++){
    if(hash[a[i]]==1){
      cout<<a[i];
      break;
    }
  }
  if(i==num) cout<<"None";
  return 0;
}