题解 | 小红的合数寻找

import java.util.Scanner;
import java.util.ArrayList;
import java.util.List;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
       Scanner scanner=new Scanner(System.in);
        int num= scanner.nextInt();
        int begin=num,end=num*2;
        List<Integer> compositeNumber=new ArrayList<>();
        for (int i = begin; i <=end ; i++) {
            for (int j=2;j<i-1;j++){
                if (i%j==0){
                    compositeNumber.add(i);
                    break;
                }
            }
        }
        if (compositeNumber.size()>=1){
            System.out.println(compositeNumber.get(0));
        }else {
            System.out.println("-1");
        }
    }
}