[PAT] 1041 Be Unique （20 分）Java

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

package pattest;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;

/**
 * @Auther: Xingzheng Wang
 * @Date: 2019/2/22 13:51
 * @Description: pattest
 * @Version: 1.0
 */
public class PAT1041 {
    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        String[] sp = reader.readLine().split(" ");

        List<String> list1 = new ArrayList<>();
        List<String> list2 = new ArrayList<>();
        for (int i = 1; i < sp.length; i++) {
            if (list1.contains(sp[i])){
                list2.add(sp[i]);
            }else{
                list1.add(sp[i]);
            }
        }
        list1.removeAll(list2);
        if (list1.size() > 0){
            System.out.print(list1.get(0));
        }else{
            System.out.print("None");
        }
    }
}