洛谷$P$2286 宠物收养场 $[HNOI2004]$ $splay$

正解:$splay$

解题报告:

传送门!

$splay$板子,,,?

先考虑这题要实现些什么东西嘛$QwQ$

其实只要实现一个东西?就查询数列中与给定数字相差最小的数,显然用$splay$查询前驱后继,然后就没辣,,,?(哦还一个$insert$,,,$QwQ$

记得分类讨论下是人有剩还是宠物有剩就好,$over$

#include<bits/stdc++.h>
using namespace std;
#define il inline
#define gc getchar()
#define ri register int
#define rb register bool
#define rc register char

const int N=1e5,mod=,inf=1e9;
int rt,n,cnt=,nod_cnt,as,a,b;
struct nod{int ch[],val,sz,fa;il void pre(ri x,ri fat){ch[]=ch[]=;val=x;sz=;fa=fat;}}tr[N];

il int read()
{
    rc ch=gc;ri x=;rb y=;
    while(ch!='-' && (ch>'' || ch<''))ch=gc;
    if(ch=='-')ch=gc,y=;
    while(ch>='' && ch<='')x=(x<<)+(x<<)+(ch^''),ch=gc;
    return y?x:-x;
}
il void pushup(ri x){tr[x].sz=tr[tr[x].ch[]].sz+tr[tr[x].ch[]].sz+;}
il void rotate(ri x)
{
    ri fa=tr[x].fa,grdfa=tr[fa].fa;rb op1=tr[fa].ch[]==x,op2=tr[grdfa].ch[]==fa;
    tr[grdfa].ch[op2]=x;tr[x].fa=grdfa;
    tr[fa].ch[op1]=tr[x].ch[op1^];tr[tr[x].ch[op1^]].fa=fa;
    tr[fa].fa=x;tr[x].ch[op1^]=fa;
    pushup(fa);pushup(x);
}
il void splay(ri x,ri goal)
{
    if(!x)return;
    while(tr[x].fa!=goal)
    {
        ri fa=tr[x].fa,grdfa=tr[fa].fa;
        if(grdfa!=goal)(tr[fa].ch[]==x)^(tr[grdfa].ch[]==fa)?rotate(x):rotate(fa);
        rotate(x);
    }
    if(!goal)rt=x;
}
il void insert(ri x)
{
    ri nw=rt,fa=;
    while(nw)fa=nw,nw=tr[nw].ch[tr[nw].val<x];
    nw=++nod_cnt;if(fa)tr[fa].ch[tr[fa].val<x]=nw;tr[nw].pre(x,fa);
    splay(nw,);
}
il void fd(ri x)
{
    ri nw=rt;if(!rt)return;
    while(tr[nw].ch[x>tr[nw].val] && x!=tr[nw].val)nw=tr[nw].ch[x>tr[nw].val];
    splay(nw,);
}
il int ask_pr(ri x)
{
    fd(x);ri nw=rt;
    if(tr[nw].val<=x)return nw;
    nw=tr[nw].ch[];
    while(tr[nw].ch[])nw=tr[nw].ch[];
    return nw;
}
il int ask_lst(ri x)
{
    fd(x);ri nw=rt;
    if(tr[nw].val>=x)return nw;
    nw=tr[nw].ch[];
    while(tr[nw].ch[])nw=tr[nw].ch[];
    return nw;
}
il int ask_pr_yg(ri x)
{
    fd(x);ri nw=rt;
    if(tr[nw].val<x)return nw;
    nw=tr[nw].ch[];
    while(tr[nw].ch[])nw=tr[nw].ch[];
    return nw;
}
il int ask_lst_yg(ri x)
{
    fd(x);ri nw=rt;
    if(tr[nw].val>x)return nw;
    nw=tr[nw].ch[];
    while(tr[nw].ch[])nw=tr[nw].ch[];
    return nw;
}
il void delet(ri x)
{
    ri pr=ask_pr_yg(x),lst=ask_lst_yg(x);
    splay(pr,);splay(lst,pr);
    tr[tr[rt].ch[]].ch[]=;
}

int main()
{
//     freopen("2286.in","r",stdin);freopen("2286.out","w",stdout);
    n=read();insert(inf);insert(-inf);
    while(n--)
    {
        cnt+=a?:-;a=read(),b=read();
        if(!cnt){insert(b);continue;}
        if(cnt>)
        {
            if(a){insert(b);continue;}
            ri pr=ask_pr(b),lst=ask_lst(b);
            if(abs(tr[lst].val-b)<abs(b-tr[pr].val))
            {
                as+=abs(tr[lst].val-b);as%=mod;
                delet(tr[lst].val);
            }
            else
            {
                as+=abs(b-tr[pr].val);as%=mod;
                delet(tr[pr].val);
            }
        }
        else
        {
            if(!a){insert(b);continue;}
            ri pr=ask_pr(b),lst=ask_lst(b);
            if(abs(tr[lst].val-b)<abs(b-tr[pr].val))
            {
                as+=abs(tr[lst].val-b);as%=mod;
                delet(tr[lst].val);
            }
            else
            {
                as+=abs(b-tr[pr].val);as%=mod;
                delet(tr[pr].val);
            }
        }
    }
    printf("%d\n",as);
    return ;
}