代码为：

#include <bits/stdc++.h>
using namespace std;

typedef long long LL;

const LL N = 80005, Mod = 1000000;

struct Node
{
	int l,r;
	LL val,key;
	LL size;
}fhq[N];
int root,cnt;
int kind; // 树里装的是人还是狗 
int n;
int x,y,z;

void pushup(int u)
{
	fhq[u].size = fhq[fhq[u].l].size + fhq[fhq[u].r].size + 1;
}

void split(int u,LL val,int &x,int &y)
{
	if(!u) 
	{
		x = y = 0;
		return ;
	}
	
	if(fhq[u].val <= val) 
	{
		x = u;
		split(fhq[u].r,val,fhq[u].r,y);
	}
	else 
	{
		y = u;
		split(fhq[u].l,val,x,fhq[u].l);
	}
	
	pushup(u);
}

int merge(int x,int y)
{
	if(!x || !y) return x | y;
	
	if(fhq[x].key >= fhq[y].key)
	{
		fhq[x].r = merge(fhq[x].r,y);
		pushup(x);
		return x;
	}
	else
	{
		fhq[y].l = merge(x,fhq[y].l);
		pushup(y);
		return y;
	}
}

mt19937 rnd(233);
int intree = 0;
int create(LL val)
{
	fhq[++cnt].val = val,fhq[cnt].key = rnd(),fhq[cnt].size = 1;
	return cnt;
}

void insert(LL val)
{
	split(root,val,x,y);
	root = merge(merge(x,create(val)),y);
}

void del(LL val)
{
//	intree --;
	split(root,val,x,z);
	split(x,val-1,x,y);
	y = merge(fhq[y].l,fhq[y].r);
	root = merge(x,merge(y,z));
//	cnt --;
}

LL pre(LL val)
{
	split(root,val-1,x,y);
	
	int u = x;
	while(fhq[u].r) u = fhq[u].r;
	
	LL res = fhq[u].val;
	
	root = merge(x,y);
	
	return res;
}

LL nxt(LL val)
{
	split(root,val,x,y);
	
	int u = y;
	while(fhq[u].l) u = fhq[u].l;

	LL res = fhq[u].val;
	
	root = merge(x,y);
	
	return res;
}

int main()
{
//	freopen("input.txt","r",stdin);
	
	scanf("%d",&n);
	
	insert(-1e10),insert(1e10);
	
	long long ans = 0;
	while(n --)
	{
		LL opt, val;
		scanf("%lld%lld",&opt,&val);
						
		if(!intree || opt == kind)
		{
			intree ++;
			insert(val);
			kind = opt;
		}
		else
		{			
			intree --;
			LL val1 = pre(val);			
			LL val2 = nxt(val);
						
			if(abs(val-val1) < abs(val-val2)) del(val1),ans = (ans + abs(val-val1)) % Mod;
			else del(val2),ans = (ans + abs(val-val2)) % Mod;
		}
	}	
	
	cout<<ans;
	
	return 0;
}

开始的时候因为没加哨兵WA了几个点，加了哨兵之后无论是本地还是Luogu IDE测试样例都是错的

抱着随便试试的想法交了，却AC了。

求原因。。。