题解 | #MP3光标位置#

究极屎

import java.util.*;
import java.lang.*;
public class Main{
     public static void main(String[] args){
         Scanner sc = new Scanner(System.in);
         int num = Integer.parseInt(sc.nextLine());
         String cmd = sc.nextLine();
         int curindex = 1;
         int head = 1;
         int foot = 4;
         List list = new ArrayList();//当前页
         for(int i=0;i<cmd.length();i++){
             if(num<=4){//小于4
                 if(cmd.charAt(i)=='U'){//上 
                     if(curindex==1){
                         curindex = num;
                     }else{
                         curindex--;
                     }
                 }
                 if(cmd.charAt(i)=='D'){
                     if(curindex==num){
                         curindex=1;
                     }else{
                         curindex++;
                     }
                 }
             }
             if(num>4){//大于4
                 if(cmd.charAt(i)=='U'){
                     if(head==1 && curindex==1){//光标在最小处   1234页
                         foot = num;
                         head = num-4+1;
                         curindex = num;
                     }else if(curindex==head && curindex!=1){//光标在头部 不等于1
                        curindex--;
                        head--;
                        foot--;//整个框都要更新
                         
                     }else if(curindex!=head){//光标不在头部
                          curindex--;//仅光标移动
                     }
                 }
                 if(cmd.charAt(i)=='D'){
                    if(foot==num && curindex==num){//光标为最大值了 num为低
                        head = 1;
                        foot = head+4-1;
                        curindex = 1;//回框
                    }else if(curindex==foot&&curindex!=num){//光标在低 但是没有到最后
                        curindex++;
                        foot++;
                        head++;
                    }else if(curindex!=foot){//光标在中间
                        curindex++;
                    }
                 }
                 
             }
         }
         StringBuilder sb = new StringBuilder();
         if(num<=4){
             for(int i=1;i<=num;i++){
                  sb.append(i).append(" ");
             }
         }else{
            for(int i = head;i<=foot;i++){
             sb.append(i).append(" ");
         }
         }
         
         System.out.println(sb);
         System.out.println(curindex);
}
}