PAT (Advanced Level) Practice A1041 Be Unique （20 分）（C++）（甲级）（散列）

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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 [1,10​4​​ ]. 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 (≤10​5) 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

using namespace std;
#include<algorithm>
#include<iostream>
#include<cstdio>
#include<cstring>

int num[10010] = {0};//每个数字出现的次数
int bet[100010] = {0};//每个人赌出的数字

int main()
{
    int N = 0;
    scanf("%d", &N);
    for(int i=0; i<N; i++)
    {
        scanf("%d", &bet[i]);
        num[bet[i]]++;//该数字出现次数累计
    }
    int flag = 0;//已经出现则置一，没有满足题意的则输出None
    for(int i=0; i<N; i++)
    {
        if(num[bet[i]] == 1)//首次赌出的唯一数字
        {
            flag = 1;
            printf("%d", bet[i]);
            break;
        }
    }
    if(!flag) printf("None");
    return 0;
}