（其实今天好热啊？
题目大意：插入，删除，k小，前驱后继，数的排名。
splay和treap裸题...过几天补个treap的
splay:
#include<iostream> #include<cstdlib> #include<cstring> #include<cstdio> #define which(x) (son[fa[x]][1]==x) using namespace std; const int extar[2]={2147483647,-2147483647}; int fa[100010],count[100010],son[100010][3],val[100010],data[100010]; int root,x,y,n,tot,xiugai; void read(int &k) {k=0;int f=1;char c=getchar();while(c<'0'||c>'9')c=='-'&&(f=-1),c=getchar();while(c<='9'&&c>='0')k=k*10+c-'0',c=getchar();k*=f; } void rotate(int x) {int f=fa[x];bool k=which(x);son[f][k]=son[x][!k];son[x][!k]=f;son[fa[f]][which(f)]=x;if(son[f][k])fa[son[f][k]]=f;fa[x]=fa[f];fa[f]=x;count[x]=count[f];count[f]=count[son[f][0]]+count[son[f][1]]+val[f]; } void splay(int x,int g) {while(fa[x]!=g){int f=fa[x];if(fa[f]==g){rotate(x);break;}if(which(x)^which(f))rotate(x);else rotate(f);rotate(x);}if(!g)root=x; } int search(int x,int y) {if(data[x]>y&&son[x][0])return search(son[x][0],y);if(data[x]<y&&son[x][1])return search(son[x][1],y);return x; } int ext(int x,int w) {int k=search(x,extar[w]);splay(k,0);return data[k]; } int pred(int w) {int k=search(root,w);splay(k,0);if(data[k]<w)return data[k];return ext(son[k][0],0); } int succ(int x) {int k=search(root,x);splay(k,0);if(data[k]>x)return data[k];return ext(son[k][1],1); } int rank(int x,int k) {if(k<=count[son[x][0]])return rank(son[x][0],k);if(k<=(count[son[x][0]]+val[x]))return x;return rank(son[x][1],k-count[son[x][0]]-val[x]); } int findnum(int x) {int k=search(root,x);splay(k,0);return count[son[k][0]]+1; } void insert(int &x,int w,int f) {if(!x){x=++tot;count[x]=val[x]=1;data[x]=w;fa[x]=f;xiugai=tot;return;}if(data[x]==w)val[x]++,xiugai=x;if(data[x]<w)insert(son[x][1],w,x);if(data[x]>w)insert(son[x][0],w,x);count[x]++; } void del(int w) {int k=search(root,w);splay(k,0);if(data[k]==w){if(val[k]>1)val[k]--,count[k]--;elseif(!son[k][0]){root=son[k][1];fa[root]=fa[k]=son[k][1]=count[k]=val[k]=data[k]=0;}else{fa[son[k][0]]=0;ext(son[k][0],0);son[root][1]=son[k][1];if(son[k][1])fa[son[k][1]]=root;count[root]+=count[son[k][1]];fa[k]=son[k][0]=son[k][1]=data[k]=val[k]=count[k]=0;}} } int main() {read(n);for(int i=1;i<=n;i++){read(x);read(y);switch(x){case 1:insert(root,y,0);splay(xiugai,0);root=xiugai;break;case 2:del(y);break;case 3:printf("%d\n",findnum(y));break;case 4:printf("%d\n",data[rank(root,y)]);break;case 5:printf("%d\n",pred(y));break;case 6:printf("%d\n",succ(y));break;default:break;}} }
