PAT (Advanced Level) Practise 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

题意：给你n个数，输出其中只出现了一次的数

#include <iostream>#include <cstdio>#include <cmath>#include <cstring>#include <algorithm>#include <stack>#include <queue>#include <vector>#include <map>using namespace std;const int N=200010;const int INF=0x7FFFFFFF;int a[100005];int x[100005];int main(){    int n;    while(~scanf("%d",&n))    {        memset(x,0,sizeof x);        for(int i=0;i<n;i++)        {            scanf("%d",&a[i]);            x[a[i]]++;        }        int flag=0;        for(int i=0;i<n;i++)        {            if(x[a[i]]==1)            {                flag=1;                printf("%d\n",a[i]);                break;            }        }        if(!flag) printf("None\n");    }    return 0;}