营业额统计 HYSBZ - 1588

https://www.lydsy.com/JudgeOnline/problem.php?id=1588

伸展树模板题 在这题里就是普通二叉树 只不过每次要把新插入的节点splay到根节点之下 可达到均摊nlogn 大概这就是充满玄学的局部性原理了。。

线段树或者排序乱搞都可以

#include <bits/stdc++.h>
using namespace std;
#define ll long long
const ll N=0x3f3f3f3f3f3f3f3f;

struct node;
node *null;

struct node
{
    node *ch[2],*fa;
    ll val;
    int sz;
    void wipe()
    {
        fa=ch[0]=ch[1]=null;
        sz=0,val=0;
    }
    void setc(node *tmp,int d)
    {
        ch[d]=tmp;
        tmp->fa=this;
    }
    bool getd()
    {
        return fa->ch[1]==this;
    }
    void pushup()
    {
        sz=ch[0]->sz+ch[1]->sz+1;
    }
};

node *mp[50010];
node *root,*tail;
node pool[50010];
ll ary[50010];
int n;

void init()
{
    node *tmp;
    int i;
    tail=pool;
    null=tail++;
    null->fa=null->ch[0]=null->ch[1]=null;
    null->sz=null->val=0;
    tmp=tail++;
    tmp->wipe();
    root=tmp;
    tmp=tail++;
    tmp->wipe();
    root->setc(tmp,1);
}

node *insert(node *&cur,node *fa,ll val)
{
    node *res;
    if(cur==null)
    {
        cur=tail++;
        cur->wipe();
        cur->fa=fa;
        cur->sz=1,cur->val=val;
        return cur;
    }
    if(val<=cur->val) res=insert(cur->ch[0],cur,val);
    else res=insert(cur->ch[1],cur,val);
    cur->pushup();
    return res;
}

void rotate(node *cur)
{
    node *f,*ff;
    int c,cc;
    f=cur->fa,ff=cur->fa->fa;
    c=cur->getd(),cc=f->getd();
    f->setc(cur->ch[!c],c);
    cur->setc(f,!c);
    if(ff->ch[cc]==f) ff->setc(cur,cc);
    else cur->fa=ff;
    f->pushup();
}

void splay(node *cur,node *tar)
{
    while(cur->fa!=tar)
    {
        if(cur->fa->fa==tar) rotate(cur);
        else
        {
            if(cur->getd()==cur->fa->getd()) rotate(cur->fa);
            else rotate(cur);
            rotate(cur);
        }
    }
    cur->pushup();
}

node *getpre(node *cur)
{
    cur=cur->ch[0];
    while(cur->ch[1]!=null) cur=cur->ch[1];
    return cur;
}

node *getnext(node *cur)
{
    cur=cur->ch[1];
    while(cur->ch[0]!=null) cur=cur->ch[0];
    return cur;
}

ll getabs(ll val)
{
    if(val>0) return val;
    else return -val;
}

int main()
{
    node *pre,*nxt;
    ll ans,minn;
    int i;
    scanf("%d",&n);
    for(i=1;i<=n;i++) scanf("%lld",&ary[i]);
    init();
    for(i=1;i<=n;i++)
    {
        mp[i]=insert(root->ch[1]->ch[0],root->ch[1],ary[i]);
        splay(mp[i],root->ch[1]);
        if(i==1) ans=ary[i];
        else
        {
            pre=getpre(mp[i]);
            nxt=getnext(mp[i]);
            minn=N;
            if(pre!=null) minn=min(minn,getabs(pre->val-ary[i]));
            if(nxt!=null) minn=min(minn,getabs(nxt->val-ary[i]));
            ans+=minn;
        }
    }
    printf("%lld\n",ans);
    return 0;
}