95分 WA第五个点 求助 有用闭关

#include<bits/stdc++.h>
using namespace std;
const int maxn=5*1e5+20;
int n,m;
struct Node{
	int prev,next;//分别代表前面的数与后面的数 
}l[maxn];
inline int read()//快读 
{
    int x=0,f=1;
    char ch=getchar();
    while(ch<'0'||ch>'9')
    {
        if(ch=='-')
            f=-1;
        ch=getchar();
    }
    while(ch>='0' && ch<='9')
        x=x*10+ch-'0',ch=getchar();
    return x*f;
}
bool panlian(int x)
{
	return l[x].next!=0||l[x].prev!=0;
}
void shan(int x)
{
    if(!panlian(x))
    {
        return ;
    }
    if(l[x].prev != 0)
    {
        l[l[x].prev].next = l[x].next;  
    }
    if(l[x].next != 0)
    {
        l[l[x].next].prev = l[x].prev;  
    }
    l[x].prev = l[x].next = 0;
}
void left(int x,int y)
{
	if(panlian(x))
    {
        shan(x);
	}
	l[x].next =y;
	l[x].prev =l[y].prev ;
	if(l[y].prev!=0)
	{
		l[l[y].prev].next=x;
	}
	l[y].prev=x;
	return ;
}
void right(int x,int y)
{
	if(panlian(x))
    {
    	shan(x);
	}
	l[x].prev=y;
	l[x].next=l[y].next;
	if(l[y].next!=0)
	{
		l[l[y].next].prev=x;
	}
	l[y].next=x;
	return ;
}
int main(){
	ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
	n=read();
	m=read();
	for(int i=1;i<=n;i++)
	{
		if(i!=1)
		{
		   l[i].prev=i-1;
		}
		if(i!=n)
		{
		   l[i].next=i+1;
		}
	}
	l[1].prev=0;
	l[n].next=0;
	while(m--)
    {
    	int op,x,y;
    	op=read();
		if(op==1)
		{
			x=read();
			y=read();
			if(x==y)
			{
				continue;
			}
			else
			{
				left(x,y);
			}
		}
		else if(op==2)
		{
			x=read();
			y=read();
			if(x==y)
			{
				continue;
			}
			else
			{
				right(x,y);
			}
		}
		else
		{
			x=read();
			shan(x);
		} 
	}
	int head=0;
	for(int i=1;i<=n;i++)
	{
		if(l[i].prev ==0&&panlian(i))
		{
			head=i;
			break;
		}
	}
	if(head==0)
	{
		cout<<"Empty!"<<endl;
	}
	else
	{
		int xian=head;
		while(xian!=0)
		{
			cout<<xian<<" ";
			xian=l[xian].next;
		}
		cout<<endl;
	}
	return 0;
}