题解：
splay模板
删除，翻转等等
代码：
#include<cstdio> #include<cstring> #include<cmath> #include<algorithm> using namespace std; const int M=200010; int root,N,ch[M][2],pre[M],a[M],size[M],key[M],add[M],rev[M],s[M],tot2,tot1; #define Key_value ch[ch[root][1]][0] void NewNode(int &r,int f,int val) { if (tot2)r=s[tot2--]; else r+=++tot1; ch[r][0]=ch[r][1]=0; pre[r]=f; size[r]=1; key[r]=val; rev[r]=0; add[r]=0; } void pushup(int r){size[r]=size[ch[r][0]]+size[ch[r][1]]+1;} void build(int &x,int l,int r,int f) { if (l>r)return; int mid=(l+r)>>1; NewNode(x,f,a[mid]); build(ch[x][0],l,mid-1,x); build(ch[x][1],mid+1,r,x); pushup(x); } void update_add(int r,int x) { if (!r)return; add[r]+=x; key[r]+=x; } void update_rev(int r) { if (!r)return; swap(ch[r][1],ch[r][0]); rev[r]^=1; } void pushdown(int r) { if (add[r]) { update_add(ch[r][0],add[r]); update_add(ch[r][1],add[r]); add[r]=0; } if (rev[r]) { update_rev(ch[r][0]); update_rev(ch[r][1]); rev[r]=0; } } void Rotate(int x,int kind) { int y=pre[x]; pushdown(y); pushdown(x); ch[y][!kind]=ch[x][kind]; pre[ch[x][kind]]=y; if (pre[y])ch[pre[y]][ch[pre[y]][1]==y]=x; pre[x]=pre[y]; ch[x][kind]=y; pre[y]=x; pushup(y); } void Splay(int r,int goal) { pushdown(r); while(pre[r]!=goal) { if (pre[pre[r]]==goal) { pushdown(pre[r]); pushdown(r); Rotate(r,ch[pre[r]][0]==r); } else { pushdown(pre[pre[r]]); pushdown(pre[r]); pushdown(r); int y=pre[r],kind=(ch[pre[y]][0]==y); if (ch[y][kind]==r) { Rotate(r,!kind); Rotate(r,kind); } else { Rotate(y,kind); Rotate(r,kind); } } } pushup(r); if (goal==0)root=r; } int get_kth(int r,int k) { pushdown(r); int t=size[ch[r][0]]+1; if (t==k)return r; if (t>k)return get_kth(ch[r][0],k); else return get_kth(ch[r][1],k-t); } void change(int &poss,int k) { int pos=get_kth(root,poss); Splay(pos,0); int tmp=size[ch[root][0]]+1; Splay(get_kth(root,1),0); Splay(get_kth(root,tmp),root); tmp=Key_value; Key_value=0; pushup(ch[root][1]); pushup(root); Splay(get_kth(root,size[root]-1),0); Key_value=tmp; pre[Key_value]=ch[root][1]; pushup(ch[root][1]); pushup(root); Splay(get_kth(root,1),0); Splay(get_kth(root,k+2),root); } void Add(int &poss,int k2,int x) { change(poss,k2); update_add(Key_value,x); pushup(ch[root][1]); pushup(root); poss=2; } void Reverse(int &poss,int k1) { change(poss,k1); update_rev(Key_value); pushup(ch[root][1]); pushup(root); poss=2; } void Insert(int &poss,int x) { int pos=get_kth(root,poss); Splay(pos,0); Splay(get_kth(root,size[ch[root][0]]+2),root); NewNode(Key_value,ch[root][1],x); pushup(ch[root][1]); pushup(root); } void erase(int r) { if (r) { s[++tot2]=r; erase(ch[r][0]); erase(ch[r][1]); } } void Delete(int &poss) { int pos=get_kth(root,poss); Splay(pos,0); int tmp=size[ch[root][0]]+1; Splay(get_kth(root,tmp-1),0); Splay(get_kth(root,tmp+1),root); erase(Key_value); pre[Key_value]=0; Key_value=0; pushup(ch[root][1]); pushup(root); if (tmp==size[root])poss=2; else poss=tmp; } void Move(int &poss,int x) { int pos=get_kth(root,poss); if (x==1) { Splay(pos,0); int tmp=size[ch[root][0]]; if (size[ch[root][0]]==1)tmp=size[root]-1; poss=tmp; } else { Splay(pos,0); int tmp=size[ch[root][0]]+2; if (tmp==size[root])tmp=2; poss=tmp; } } int Query(int &poss) { int pos=get_kth(root,poss); Splay(pos,0); return key[root]; } int main() { int n,m,k1,k2,t=1; while(scanf("%d%d%d%d",&n,&m,&k1,&k2)!=EOF) { N=n; if (n==0&&m==0&&k1==0&&k2==0)break; printf("Case #%d: ",t++); for (int i=1;i<=n;i++)scanf("%d",&a[i]); int poss=2,sum=n; root=tot1=tot2=0; ch[root][0]=ch[root][1]=size[root]=key[root]=add[root]=pre[root]=0; rev[root]=0; NewNode(root,0,-1); NewNode(ch[root][1],root,-1); build(Key_value,1,N,ch[root][1]); pushup(ch[root][1]); pushup(root); for (int i=1;i<=m;i++) { char a[50]; scanf("%s",a); if (a[0]=='q') { int res=Query(poss); printf("%d ",res); } else if (a[0]=='r')Reverse(poss,k1); else if (a[0]=='i') { int x; sum+=1; scanf("%d",&x); Insert(poss,x); } else if (a[0]=='d') { sum-=1; Delete(poss); } else if (a[0]=='m') { int x; scanf("%d",&x); if (x==1) { if (poss==2)poss=sum+1; else poss-=1; } if (x==2) { if (poss==sum+1)poss=2; else poss+=1; } } else if (a[0]=='a') { int x; scanf("%d",&x); Add(poss,k2,x); } } } return 0; }