题解 | #MP3光标位置#

//模拟方法

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;

public class Main {
    public static void main(String[] args) throws IOException {
        Scanner scan = new Scanner(System.in);
        int num = scan.nextInt();
        String str = scan.next();
        int index =1;
        int pageStart = 0;
        for(int i=0;i<str.length();i++){
            if(str.charAt(i) == 'U'){
                if(index -1==0){
                    pageStart = num > 3?num-3:num;    //要点
                    index = num;
                }else{
                    if(index == pageStart){    
                        pageStart -=1;
                    }
                    index -= 1;
                }
            }else{
                if(index +1 == num+1){     //要点
                    pageStart = 1;
                    index = 1;
                }else{
                    if(index == pageStart+3){    //要点
                        pageStart +=1;
                    }
                    index +=1 ;   
                }
            }
        }
        for(int i=0;i<4&&pageStart<=num;i++){
            System.out.print(pageStart+" ");
            pageStart++;
        }
        System.out.println();
        System.out.println(index);
    }
}  、、