BZOJ 1251 Splay维护序列

思路：
splay维护序列的裸题
啊woc调了一天
感谢yzy大佬的模板……

//By SiriusRen#include <cstdio>#include <cstring>#include <algorithm>using namespace std;#define N 55555#define inf 0x3f3f3f3fint n,m,root,cnt,size[N],ch[N][2],fa[N],v[N],mx[N],rev[N],tag[N];int build(int l,int r){    if(l>r)return 0;    if(l==r){size[l]=1;return l;}    int mid=(l+r)>>1;    ch[mid][0]=build(l,mid-1);fa[ch[mid][0]]=mid;    ch[mid][1]=build(mid+1,r);fa[ch[mid][1]]=mid;    size[mid]=size[ch[mid][0]]+size[ch[mid][1]]+1;    return mid;}void push_up(int x){    mx[0]=-inf;    size[x]=size[ch[x][0]]+size[ch[x][1]]+1;    mx[x]=max(mx[ch[x][0]],max(mx[ch[x][1]],v[x]));}void push_down(int x){    if(rev[x]){rev[ch[x][0]]^=1,rev[ch[x][1]]^=1,swap(ch[x][0],ch[x][1]);rev[x]^=1;}    if(tag[x]){        tag[ch[x][0]]+=tag[x],tag[ch[x][1]]+=tag[x];        mx[ch[x][0]]+=tag[x],mx[ch[x][1]]+=tag[x];        v[ch[x][0]]+=tag[x],v[ch[x][1]]+=tag[x];        tag[x]=0;    }}void rotate(int p){    int q=fa[p],y=fa[q],x=(ch[q][1]==p);    ch[q][x]=ch[p][!x],fa[ch[q][x]]=q;    ch[p][!x]=q;fa[q]=p;fa[p]=y;    if(y){        if(ch[y][0]==q)ch[y][0]=p;        else ch[y][1]=p;    }push_up(q);}void Splay(int x,int tp){    for(int y;y=fa[x];rotate(x)){        if(y==tp)break;        if(fa[y]!=tp){            if((ch[y][0]==x)^(ch[fa[y]][0]==y))rotate(x);            else rotate(y);        }    }push_up(x);    if(!tp)root=x;}int find(int x,int num){    push_down(x);    if(size[ch[x][0]]+1==num)return x;    else if(size[ch[x][0]]+1>num)return find(ch[x][0],num);    else return find(ch[x][1],num-size[ch[x][0]]-1);}void add(int l,int r,int wei){    int y=find(root,l);    Splay(y,0),Splay(find(root,r+2),y);    int V=ch[ch[root][1]][0];    tag[V]+=wei,v[V]+=wei;mx[V]+=wei;}void reverse(int l,int r){    int y=find(root,l);    Splay(y,0),Splay(find(root,r+2),y);    rev[ch[ch[root][1]][0]]^=1;}void get_max(int l,int r){    int y=find(root,l);    Splay(y,0),Splay(find(root,r+2),y);    printf("%d\n",mx[ch[ch[root][1]][0]]);}int main(){    int op,l,r,wei;    scanf("%d%d",&n,&m);    root=build(1,n+2);    mx[0]=v[1]=v[n+2]=mx[1]=mx[n+2]=-inf;    for(int i=1;i<=m;i++){        scanf("%d%d%d",&op,&l,&r);        if(op==1)scanf("%d",&wei),add(l,r,wei);        else if(op==2)reverse(l,r);        else get_max(l,r);    }}