SPOJ GSS6 Can you answer these queries VI ——Splay

#include <cstdio>
#include <cstring>
#include <cmath>
#include <cstdlib>

#include <map>
#include <set>
#include <queue>
#include <string>
#include <iostream>
#include <algorithm>

using namespace std;

#define maxn 500005
#define eps 1e-8
#define db double
#define L ch[x][0]
#define R ch[x][1]
#define ll long long
#define inf 0x3f3f3f3f
#define F(i,j,k) for (int i=j;i<=k;++i)
#define D(i,j,k) for (int i=j;i>=k;--i)

void Finout()
{
    #ifndef ONLINE_JUDGE
    freopen("in.txt","r",stdin);
    freopen("wa.txt","w",stdout);
    #endif
}

int Getint()
{
    int x=0,f=1; char ch=getchar();
    while (ch<‘0‘||ch>‘9‘) {if (ch==‘-‘) f=-1; ch=getchar();}
    while (ch>=‘0‘&&ch<=‘9‘) {x=x*10+ch-‘0‘; ch=getchar();}
    return x*f;
}

int ch[maxn][2],sum[maxn],lx[maxn],rx[maxn],mx[maxn],fa[maxn],siz[maxn],v[maxn];
int a[maxn],n,rt,q,tot;

void update(int x)
{
	siz[x]=siz[L]+siz[R]+1;
	sum[x]=sum[L]+sum[R]+v[x];
	mx[x]=lx[x]=rx[x]=v[x];
	if (x==1)
	{
		mx[x]=mx[R];
		lx[x]=lx[R];
		rx[x]=rx[R];
		return ;
	}
	if (x==n+2)
	{
		mx[x]=mx[L];
		lx[x]=lx[L];
		rx[x]=rx[L];
		return ;
	}
	if (((!L))&&((!R))) lx[x]=rx[x]=mx[x]=sum[x]=v[x];
	else if ((!L))
	{
		lx[x]=max(v[x],v[x]+lx[R]);
		rx[x]=max(rx[R],sum[R]+v[x]);
		mx[x]=max(v[x],max(mx[R],v[x]+lx[R]));
		mx[x]=max(mx[x],max(lx[x],rx[x]));
	}
	else if ((!R))
	{
		lx[x]=max(lx[L],sum[L]+v[x]);
		rx[x]=max(v[x],v[x]+rx[L]);
		mx[x]=max(v[x],max(mx[L],rx[L]+v[x]));
		mx[x]=max(mx[x],max(lx[x],rx[x]));
	}
	else
	{
		lx[x]=max(lx[L],max(sum[L]+v[x],sum[L]+v[x]+lx[R]));
		rx[x]=max(rx[R],max(sum[R]+v[x],sum[R]+v[x]+rx[L]));
		mx[x]=max(mx[L],max(mx[R],max(rx[L],0)+v[x]+max(lx[R],0)));
		mx[x]=max(mx[x],max(lx[x],rx[x]));
	}
}

void rot(int x,int &k)
{
	int y=fa[x],z=fa[y],l,r;
	if (ch[y][0]==x) l=0; else l=1; r=l^1;
	if (y==k) k=x;
	else
	{
		if (ch[z][0]==y) ch[z][0]=x;
		else ch[z][1]=x;
	}
	fa[x]=z; fa[y]=x; fa[ch[x][r]]=y;
	ch[y][l]=ch[x][r];ch[x][r]=y;
	update(y); update(x);
}

void splay(int x,int &k)
{
	while (x!=k)
	{
		int y=fa[x],z=fa[y];
		if (y!=k)
		{
			if ((ch[z][0]==y)^(ch[y][0]==x)) rot(x,k);
			else rot(y,k);
		}
		rot(x,k);
	}
}

int find(int x,int f)
{
	if (f<=siz[L]) return find(L,f);
	else if (f==(siz[L]+1)) return x;
	else return find(R,f-siz[L]-1);
}

int build(int l,int r,int lst)
{
	int mid=l+r>>1;
	v[mid]=a[mid]; fa[mid]=lst;
	ch[mid][0]=l<mid?build(l,mid-1,mid):0;
	ch[mid][1]=r>mid?build(mid+1,r,mid):0;
	update(mid);
	return mid;
}

void debug()
{
	printf("The Tree‘s root is %d\n",rt);
	F(i,1,15) printf("Node %d : fa %d L %d R %d lx %d rx %d mx %d sum %d siz %d\n",i,fa[i],ch[i][0],ch[i][1],lx[i],rx[i],mx[i],sum[i],siz[i]);
}

int fx,fy;

int main()
{
	Finout();
	n=Getint();
	F(i,1,n) a[i+1]=Getint();
	rt=build(1,n+2,0); tot=n+2;
//	debug();
	q=Getint(); char opt[11];int x,y;
	F(i,1,q)
	{
		scanf("%s",opt);
		switch(opt[0])
		{
			case ‘Q‘:
				x=Getint();y=Getint();
//				printf("%d %d\n",x,y);
				fx=find(rt,x),fy=find(rt,y+2);
//				printf("%d %d\n",fx,fy);
				splay(fx,rt); splay(fy,ch[fx][1]);
				printf("%d\n",mx[ch[ch[fx][1]][0]]);
				update(fy); update(fx);
			break;
			case ‘I‘:
				++tot; x=Getint();y=Getint();
				v[tot]=y;
				fx=find(rt,x),fy=find(rt,x+1);
				splay(fx,rt);splay(fy,ch[fx][1]);
				fa[tot]=fy; ch[fy][0]=tot;
				update(tot); update(fy); update(fx);
			break;
			case ‘R‘:
				x=Getint();y=Getint();
				fx=find(rt,x+1); splay(fx,rt);
				v[fx]=y;update(fx);
			break;
			case ‘D‘:
				x=Getint();
				fx=find(rt,x); fy=find(rt,x+2);
				splay(fx,rt); splay(fy,ch[fx][1]);
				ch[fy][0]=0; update(fy); update(fx);
			break;
		}
//		debug();
	}
}