bzoj 1208: [HNOI2004]宠物收养所

#include<iostream>
#include<cstdio>
using namespace std;
int n,size,rt,kind,t1,t2;
long long ans;
int tr[80001][2],num[80001],fa[80001];
void rotate(int x,int &k)
{
int y=fa[x],z=fa[y],l,r;
if(tr[y][0]==x)l=0;else l=1;r=l^1;
if(y==k)k=x;
else{if(tr[z][0]==y)tr[z][0]=x;else tr[z][1]=x;}
fa[x]=z;fa[y]=x;fa[tr[x][r]]=y;
tr[y][l]=tr[x][r];tr[x][r]=y;
}
void splay(int x,int &k)
{
int y,z;
while(x!=k)
{
y=fa[x],z=fa[y];
if(y!=k)
{
if((tr[y][0]==x)^(tr[z][0]==y))rotate(x,k);
else rotate(y,k);
}
rotate(x,k);
}
}
void ins(int &k,int x,int last)
{
if(k==0){size++;k=size;num[k]=x;fa[k]=last;splay(k,rt);return;}
if(x<num[k])ins(tr[k][0],x,k);else ins(tr[k][1],x,k);
}
void del(int x)
{
splay(x,rt);
if(tr[x][0]*tr[x][1]==0)
{rt=tr[x][0]+tr[x][1];}
else
{
int k=tr[x][1];
while(tr[k][0])k=tr[k][0];
tr[k][0]=tr[x][0];fa[tr[x][0]]=k;
rt=tr[x][1];
}
fa[rt]=0;
}
void ask_before(int k,int x)
{
if(k==0)return;
if(num[k]<=x){t1=k;ask_before(tr[k][1],x);}
else ask_before(tr[k][0],x);
}
void ask_after(int k,int x)
{
if(k==0)return;
if(num[k]>=x){t2=k;ask_after(tr[k][0],x);}
else ask_after(tr[k][1],x);
}

int main()
{
scanf("%d",&n);
int f,x;
for(int i=1;i<=n;i++)
{
scanf("%d%d",&f,&x);
if(!rt){kind=f;}
if(kind==f){ins(rt,x,0);
}
else
{
t1=t2=-1;
ask_before(rt,x);ask_after(rt,x);
if(t1==-1){ans+=num[t2]-x;ans%=1000000;del(t2);}
else if(t2==-1){ans+=x-num[t1];ans%=1000000;del(t1);}
else
{
if(x-num[t1]>num[t2]-x)  {ans+=num[t2]-x;ans%=1000000;del(t2);}
else{ans+=x-num[t1];ans%=1000000;del(t1);}
}
}
}
cout<<ans<<endl;
return 0;
}