BZOJ1861 [Zjoi2006]Book 书架

Posted 2020-10-21 大奕哥&VANE

  1 #include<bits/stdc++.h>
  2 using namespace std;
  3 const int N=8e4+5;
  4 const int inf=1e9;
  5 int fa[N],c[N][2],size[N],pos[N],a[N],v[N],n,m,rt;
  6 void update(int x)
  7 {
  8     size[x]=size[c[x][0]]+size[c[x][1]]+1;
  9 }
 10 void rotate(int x,int &k)
 11 {
 12     int y=fa[x],z=fa[y];
 13     int l=(c[y][1]==x);int r=l^1;
 14     if(y==k)k=x;else c[z][c[z][1]==y]=x;
 15     fa[x]=z;fa[y]=x;fa[c[x][r]]=y;
 16     c[y][l]=c[x][r];c[x][r]=y;
 17     update(y);update(x);
 18 }
 19 void splay(int x,int &k)
 20 {
 21     while(x!=k)
 22     {
 23         int y=fa[x],z=fa[y];
 24         if(y!=k)
 25         {
 26             if(x==c[y][0]^y==c[z][0])rotate(x,k);
 27             else rotate(y,k);
 28         }
 29         rotate(x,k);
 30     }
 31 }
 32 int find(int x,int k)
 33 {
 34     if(size[c[x][0]]+1==k)return x;
 35     else if(size[c[x][0]]>=k)return find(c[x][0],k);
 36     else return find(c[x][1],k-size[c[x][0]]-1);
 37 }
 38 void del(int k)
 39 {
 40     int x=find(rt,k-1);int y=find(rt,k+1);
 41     splay(x,rt);splay(y,c[x][1]);
 42     int z=c[y][0];c[y][0]=0;fa[z]=size[z]=0;
 43     update(y);update(x);
 44 }
 45 void remove(int q,int w)
 46 {
 47     int k=pos[q],rank,x,y;
 48     
 49     splay(k,rt);rank=size[c[rt][0]]+1;
 50     del(rank);
 51     if(w==inf)x=find(rt,n),y=find(rt,n+1);
 52     else if(w==-inf)x=find(rt,1),y=find(rt,2);
 53     else x=find(rt,rank+w-1),y=find(rt,rank+w);
 54     splay(x,rt);splay(y,c[x][1]);
 55     size[k]=1;fa[k]=y;c[y][0]=k;
 56     update(y);update(x);
 57 }
 58 void build(int l,int r,int f)
 59 {
 60     if(l>r)return;
 61     int mid=l+r>>1;
 62     fa[mid]=f;c[f][mid>=f]=mid;v[mid]=a[mid];
 63     if(l==r)
 64     {
 65         size[l]=1;return;
 66     }
 67     build(l,mid-1,mid);build(mid+1,r,mid);
 68     update(mid);
 69     return;
 70 }
 71 int main()
 72 {
 73     scanf("%d%d",&n,&m);
 74     for(int i=2;i<=n+1;++i)
 75     {
 76         scanf("%d",&a[i]);pos[a[i]]=i;
 77     }
 78     build(1,n+2,0);rt=(n+3)>>1;char s[10];int k,ss,t;
 79     for(int i=1;i<=m;++i)
 80     {
 81         scanf("%s",s);
 82         if(s[0]==‘Q‘)
 83         {
 84             scanf("%d",&k);
 85             printf("%d\n",v[find(rt,k+1)]);
 86         }
 87         else if(s[0]==‘T‘)
 88         {
 89             scanf("%d",&k);
 90             remove(k,-inf);
 91         }
 92         else if(s[0]==‘B‘)
 93         {
 94             scanf("%d",&k);
 95             remove(k,inf);
 96         }
 97         else if(s[0]==‘I‘)
 98         {
 99             scanf("%d%d",&ss,&t);remove(ss,t);
100         }
101         else
102         {
103             scanf("%d",&k);k=pos[k];
104             splay(k,rt);
105             printf("%d\n",size[c[rt][0]]-1);
106         }
107     }
108     return 0;
109 }