PAT_A1041#Be Unique

Source:

PAT A1041 Be Unique (20 分)

Description:

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

Keys:

• 哈希映射

Code:

 /*
 Data: 2019-07-21 20:19:03
 Problem: PAT_A1041#Be Unique
 AC: 07:07

 题目大意：
 找出数列中仅出现一次的数
 */

 #include<cstdio>
 using namespace std;
 const int M=1e5+;
 int lot[M],mp[M]={};

 int main()
 {
 #ifdef    ONLINE_JUDGE
 #else
     freopen("Test.txt", "r", stdin);
 #endif

     int n;
     scanf("%d", &n);
     for(int i=; i<n; i++)
     {
         scanf("%d", &lot[i]);
         mp[lot[i]]++;
     }
     for(int i=; i<n; i++)
     {
         if(mp[lot[i]]==)
         {
             printf("%d", lot[i]);
             n=;break;
         }
     }
     if(n)   printf("None");

     return ;
 }