HNOI2002 营业额统计

题目思路：splay,用到了查找树内某结点的前驱，后继和插入操作。

#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<string>
#include<queue>
#include<algorithm>
#include<vector>
#include<stack>
#include<list>
#include<iostream>
#include<map>
using namespace std;
#define inf 0x3f3f3f3f
#define Max 40000
int max(int a,int b)
{
	return a>b?a:b;
}
int min(int a,int b)
{
	return a<b?a:b;
}
int p[Max],ch[Max][2],val[Max],root,top1;
inline void newnode(int &x,int fa,int data)
{
    x=++top1;
    p[x]=fa,val[x]=data;
    ch[x][0]=ch[x][1]=0;
}
inline void rot(int x,int f)
{
    int y=p[x];
    ch[y][!f]=ch[x][f];
    p[ch[x][f]]=y;
    if(p[y]) ch[p[y]][ch[p[y]][1]==y]=x;
    p[x]=p[y];
    ch[x][f]=y;
    p[y]=x;
}
inline void splay(int x,int goal)
{
    while(p[x]!=goal)
    {
        if(p[p[x]]==goal)
            rot(x,ch[p[x]][0]==x);
        else
        {
            int y=p[x];
            int f=(ch[p[y]][0]==y);
            if(ch[y][f]==x)
            {
                rot(x,!f),rot(x,f);
            }
            else
            {
                rot(y,f),rot(x,f);
            }
        }
    }
    if(goal==0) root=x;
}
inline int pre(int x)
{
    int tmp=ch[x][0];
    if(tmp==0)
    return inf;
    while(ch[tmp][1])
    {
        tmp=ch[tmp][1];
    }
    return val[x]-val[tmp];
}
inline int suc(int x)
{
    int tmp=ch[x][1];
    if(tmp==0)
        return inf;
    while(ch[tmp][0])
        tmp=ch[tmp][0];
    return val[tmp]-val[x];
}
inline int ins(int data)
{
    int x=root;
    while(ch[x][val[x]<data])
    {
        if(val[x]==data)
        {
            splay(x,0);
            return 0;
        }
        x=ch[x][val[x]<data];
    }
    newnode(ch[x][val[x]<data],x,data);
    splay(ch[x][val[x]<data],0);
    return 1;
}
int main()
{
    int n,a,b,ans,i,tmp;
    while(scanf("%d",&n)!=EOF)
    {
        ans=0;
        top1=0;
        for(i=1;i<=n;i++)
        {
            if(scanf("%d",&tmp)==EOF)
            tmp=0;
            if(i==1)
            {
                newnode(root,0,tmp);
                ans+=tmp;continue;
            }
            if(ins(tmp)==0)continue;
            a=pre(root);
            b=suc(root);
            if(a<b)
                ans+=a;
            else
                ans+=b;
        }
        printf("%d\n",ans);
    }
}