纪念第一题写出来了
import java.util.Scanner; // 注意类名必须为 Main, 不要有任何 package xxx 信息 public class Main { public static StringBuilder sb=new StringBuilder(); public static void main(String[] args) { Scanner in = new Scanner(System.in); // 注意 hasNext 和 hasNextLine 的区别 int target=in.nextInt(); count2233(target); System.out.println(sb.toString()); } public static void count2233(int target){ if (target==1){ sb.insert(0,2); return; } if (target==2){ sb.insert(0,3); return; } if (target%2==0){ sb.insert(0,3); count2233((target-2)/2); }else { sb.insert(0,2); count2233((target-1)/2); } } }