MP3光标移动

#include<iostream>
#include<string.h>
using namespace std;

int main()
{
    int N;
    cin>>N;
    int first = 1;
    int last = N;

    int start = 1;
    int length = 4;

    int curr = 1;

    char str[100];
    cin>>str;
    int num = strlen(str);
    for(int i=0; i<num; i++)
    {
        char ch = str[i];
        if(ch=='U')
        {
            if(curr == first)
            {
                start = N<=4 ? start : last - 3;
                curr = N;
            }
            else if(curr == start)
            {
                start = N<=4 ? start : start - 1;
                curr = start;
            }
            else
            {
                curr = curr-1;
            }
        }
        else if(ch=='D')
        {
            if(curr == last)
            {
                start = 1;
                curr = 1;
            }
            else if(curr == start+length-1)
            {
                start = start + 1;
                curr = curr+1;
            }
            else
            {
                curr = curr+1;
            }
        }
        else
        {

        }
    }

        for(int i=start; i<start+4; i++)
        {
            if(i<=last)
            {
                cout<<i;
                if(i!=start+3 && i!= last)
                {
                    cout<<' ';
                }
            }
        }
        cout<<endl<<curr<<endl;

    return 0;
}