pat 1041. Be Unique (20)

1041. Be Unique (20)

时间限制

100 ms

内存限制

65536 kB

代码长度限制

16000 B

判题程序

Standard

作者

CHEN, Yue

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

解：开大数组，还好没卡内存，平稳渡劫。我觉得最关键的点在if(a[b[i]]==1)这里，这里b[i]保证是按照输入值的顺序进行判断的。还有一点值得注意的是：每次while循环时要将整个a数组置零。

代码：

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

int main()
{
    int n;
    int a[100000+1];
    while(cin>>n)
    {
        int temp;
        memset(a,0,sizeof(a));
        int *b=new int[n+1];
        for(int i=0;i<n;i++)
        {
            cin>>temp;
            b[i]=temp;
            a[temp]++;
        }
        int tob=0;
        for(int i=0;i<n;i++)
        {
            if(a[b[i]]==1)
            {
                tob=1;
                cout<<b[i]<<endl;
                break;
            }
        }
        if(tob==0)
            cout<<"None"<<endl;
    }
}

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