【splay模板】

 #include <iostream>
 #include <cstring>
 #include <algorithm>
 #include <cstdio>
 #include <queue>
 #define oo 1000000000
 #define lc(x) son[x][0]
 #define rc(x) son[x][1]
 using namespace std;
 int i,j,k,n,m,s,t,ans;
 ];
 struct node
 {
     int set,rever;
 } tag[];
 ][];
 ];
 ];
 ];
 ];
 ];
 ];
 ];
 ];
 queue <int> q;
 int root,cnt,pos;
 void update(int x)
 {
     size[x] = size[lc(x)]+size[rc(x)]+;
     tsum[x] = tsum[lc(x)]+tsum[rc(x)]+key[x];
     lmax[x] = max(lmax[lc(x)],tsum[lc(x)]+key[x]+lmax[rc(x)]);
     rmax[x] = max(rmax[rc(x)],tsum[rc(x)]+key[x]+rmax[lc(x)]);
     tmax[x] = max(max(tmax[lc(x)],tmax[rc(x)]),lmax[rc(x)]+key[x]+rmax[lc(x)]);
 }
 void Round(int x)
 {
     swap(lc(x),rc(x));
     swap(lmax[x],rmax[x]);
 }
 void build(int l,int r,int &x)
 {
     if (l>r)
     {
         x = ;
         return;
     }
     if (l==r)
     {
         if (!q.empty())
         {
             x = q.front();
             q.pop();
         } else x = ++cnt;
         tag[x].rever = ;
         tag[x].;
         key[x] = tsum[x] = tmax[x] = a[l];
         lmax[x] = rmax[x] = max(,a[l]);
         size[x] = ;
         lc(x) = rc(x) = ;
         return;
     }
     ;
     if (!q.empty())
     {
         x = q.front();
         q.pop();
     } else x = ++cnt;
     key[x] = a[mid];
     tag[x].rever = ;
     tag[x].;
     lc(x) = rc(x) = ;
     build(l,mid-,lc(x));
     build(mid+,r,rc(x));
     ) fa[lc(x)] = x;
     ) fa[rc(x)] = x;
     update(x);
 }
 void pushdown(int x)
 {
     )
     {
         tag[x].rever = ;
         tag[lc(x)].rever ^= ;
         tag[rc(x)].rever ^= ;
         Round(lc(x));
         Round(rc(x));
     }
     )
     {
         )
         {
             tag[lc(x)].set = tag[x].set;
             key[lc(x)] = tag[x].set;
             tsum[lc(x)] = tag[x].set*size[lc(x)];
             ) tmax[lc(x)] = lmax[lc(x)] = rmax[lc(x)] = tsum[lc(x)];
             else
             {
                 tmax[lc(x)] = tag[x].set;
                 lmax[lc(x)] = rmax[lc(x)] = ;
             }
         }
         )
         {
             tag[rc(x)].set = tag[x].set;
             key[rc(x)] = tag[x].set;
             tsum[rc(x)] = tag[x].set*size[rc(x)];
             ) tmax[rc(x)] = lmax[rc(x)] = rmax[rc(x)] = tsum[rc(x)];
             else
             {
                 tmax[rc(x)] = tag[x].set;
                 lmax[rc(x)] = rmax[rc(x)] = ;
             }
         }
         tag[x].;
     }
 }
 int find(int x,int k)
 {
     pushdown(x);
     ==k) return x;
     else if (size[lc(x)]>=k) return find(lc(x),k);
     );
 }
 void rotate(int x)
 {
     int y = fa[x],z = fa[y],w = lc(y)==x;
     pushdown(y);
     pushdown(x);
     fa[son[x][w]] = y;son[y][w^] = son[x][w];
     fa[x] = z;) son[z][rc(z)==y] = x;
     son[x][w] = y;fa[y] = x;
     update(y);
     update(x);
 }
 void splay(int x,int s)
 {
     pushdown(x);
     while (fa[x]!=s)
     {
         int y = fa[x],z = fa[y];
         if (z!=s) rotate(lc(z)==y^lc(y)==x?x:y);
         rotate(x);
     }
     update(x);
     ) root = x;
 }
 void insert(int pos)
 {
     int z;
     build(,n,z);
     int x = find(root,pos);
     );
     splay(x,);
     splay(y,root);
     lc(y) = z;
     fa[z] = y;
     update(y);
     update(x);
 }
 void del(int x)
 {
     ) return;
     del(lc(x));
     q.push(x);
     del(rc(x));
 }
 void erase(int pos,int n)
 {
     );
     int y = find(root,pos+n);
     splay(x,);
     splay(y,root);
     del(lc(y));
     lc(y) = ;
     update(y);
     update(x);
 }
 int main()
 {
     scanf("%d%d",&n,&m);
     a[] = a[n+] = -oo;
     tmax[] = -oo;
     ;i<=n+;i++) scanf("%d",&a[i]);
     build(,n+,root);
     while (m--)
     {
         ];
         scanf();
         ]=='I')
         {
             scanf("%d%d",&pos,&n);
             ;i<=n;i++)
             scanf("%d",&a[i]);
             insert(pos+);
         } ]=='D')
         {
             scanf("%d%d",&pos,&n);
             erase(pos+,n);
         } ]==]=='K')
         {
             int c;
             scanf("%d%d%d",&pos,&n,&c);
             int x = find(root,pos);
             );
             splay(x,);
             splay(y,root);
             tag[lc(y)].set = c;
             key[lc(y)] = c;
             tsum[lc(y)] = c*size[lc(y)];
             ) tmax[lc(y)] = lmax[lc(y)] = rmax[lc(y)] = tsum[lc(y)];
             else
             {
                 tmax[lc(y)] = c;
                 lmax[lc(y)] = rmax[lc(y)] = ;
             }
             update(y);
             update(x);
         } ]=='R')
         {
             scanf("%d%d",&pos,&n);
             int x = find(root,pos);
             );
             splay(x,);
             splay(y,root);
             tag[lc(y)].rever ^= ;
             Round(lc(y));
             update(y);
             update(x);
         } ]=='G')
         {
             scanf("%d%d",&pos,&n);
             int x = find(root,pos);
             );
             splay(x,);
             splay(y,root);
             printf("%d\n",tsum[lc(y)]);
         } else printf("%d\n",tmax[root]);
     }
     ;
 }

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