编程开发平衡树问题[splay][bzoj1251]

sol:
平衡树，记得赋初值，查了好久

#include
#include
#include
#include
#include
#include
#include
using namespace std;
typedef long long ll;
int n,m;
inline int read()
{
    char c;
    int res,flag=0;
    while((c=getchar())>'9'||c<'0') if(c=='-')flag=1;
    res=c-'0';
    while((c=getchar())>='0'&&c<='9') res=(res<<3)+(res<<1)+c-'0';
    return flag?-res:res;
}
const int N=51000;
int tot;
int lc[N],rc[N],fa[N],size[N];
ll Max[N],val[N],add[N];
bool rev[N];
void build(int &k,int l,int r)
{
    if(l>r) return;
    int mid=l+r>>1;
    if(!k) k=mid;
    size[k]=1;
    if(l==r) return;
    build(lc[k],l,mid-1);
    build(rc[k],mid+1,r); 
    if(lc[k]) fa[lc[k]]=k;
    if(rc[k]) fa[rc[k]]=k;
    size[k]=size[lc[k]]+size[rc[k]]+1;
}
inline void updata(int x)
{
    Max[x]=max(max(Max[lc[x]],Max[rc[x]]),val[x]);
    size[x]=size[lc[x]]+size[rc[x]]+1;
}
inline void tag_rev(int x)
{
    rev[x]=!rev[x];
    swap(lc[x],rc[x]);
}
inline void tag_down(int x)
{
    if(rev[x])
    {
        tag_rev(lc[x]);
        tag_rev(rc[x]);
        rev[x]=!rev[x];
    }
    if(add[x])
    {
        if(lc[x])
        {
            add[lc[x]]+=add[x];
            Max[lc[x]]+=add[x];
            val[lc[x]]+=add[x];
        }
        if(rc[x])
        {
            add[rc[x]]+=add[x];
            Max[rc[x]]+=add[x];
            val[rc[x]]+=add[x];
        }
        add[x]=0;
    }
}
inline void rotate(int x)
{
    int y=fa[x],z=fa[y],b;
    b=lc[y]==x?rc[x]:lc[x];
    fa[y]=x;fa[x]=z;
    if(b) fa[b]=y;
    if(z)
    {
        if(lc[z]==y) lc[z]=x;
        else rc[z]=x;
    }
    if(lc[y]==x) rc[x]=y,lc[y]=b;
    else lc[x]=y,rc[y]=b;
    updata(y);
}
int sta[N],rt;
inline void splay(int x,int f)
{
    int i;
    sta[sta[0]=1]=x;
    for(i=fa[x];i;i=fa[i]) sta[++sta[0]]=i;
    while(sta[0])
    {
        if(add[sta[sta[0]]])
        printf("%d\n",sta[sta[0]]);
        tag_down(sta[sta[0]--]); 
    }
    while(fa[x]!=f)
    {
        int y=fa[x],z=fa[y];
        if(z!=f)
        {
            if((lc[z]==y)==(lc[y]==x)) rotate(y);
            else rotate(x);
        }
        rotate(x);
    }
    if(!fa[x]) rt=x;
    updata(x);
}
int find_kth(int x,int num)
{
    tag_down(x);
    if(size[lc[x]]>=num) return find_kth(lc[x],num);
    else if(size[lc[x]]+1==num) return x;
    else return find_kth(rc[x],num-size[lc[x]]-1);
}
void sc(int x)
{
    tag_down(x);
    if(lc[x]) sc(lc[x]);
    if(val[x]>=0)
    cout<<"faq";
    if(rc[x]) sc(rc[x]);
}
int main()
{
//  freopen("seq.in","r",stdin);
//  freopen("seq.out","w",stdout);
    n=read();
    m=read();
    Max[1]=val[1]=Max[n+2]=val[n+2]=Max[0]=val[0]=-1e9;
    build(rt,1,n+2);
    int flag,l,r;
    ll v;
    for(int i=1;i<=m;++i)
    {
        flag=read();
        l=read();
        r=read()+2;
        l=find_kth(rt,l);
        r=find_kth(rt,r);
        splay(l,0);
        splay(r,l);
        if(flag==1)
        {
            scanf("%lld",&v);
            add[lc[r]]+=v;
            Max[lc[r]]+=v;
            val[lc[r]]+=v;
        }
        if(flag==2)
        {
            sta[sta[0]=1]=lc[r];
            for(int j=fa[lc[r]];j;j=fa[j]) sta[++sta[0]]=j;
            while(sta[0]) tag_down(sta[sta[0]--]);
            tag_rev(lc[r]);
        }
        if(flag==3) printf("%lld\n",Max[lc[r]]);
    } 
}