bzoj1984

树链剖分在边上的应用
比维护点稍微麻烦一点，是对每条边标号，并且要记录每个点父亲边的编号和重儿子
然后注意各种细节
线段树上和bzoj1858的维护方法类似，覆盖的优先级高于加
具体见程序，完全是为了提升状态的练习

 type node=record
        po,next,num:longint;
      end;

 var son,a,d,fa,fp,f2,b,c,p,size,top:array[..] of longint;
     w:array[..] of node;
     tree,laz1,laz2:array[..*] of longint;
     x,y,z,i,n,t:longint;
     ch:char;
     s:string;

 function max(a,b:longint):longint;
   begin
     if a>b then exit(a) else exit(b);
   end;

 procedure add(x,y,c:longint);
   begin
     inc(t);
     w[t].po:=y;
     w[t].num:=c;
     w[t].next:=p[x];
     p[x]:=t;
   end;

 procedure swap(var a,b:longint);
   var c:longint;
   begin
     c:=a;
     a:=b;
     b:=c;
   end;

 procedure push(i:longint);
   begin
     if laz1[i]<>- then
     begin
       tree[i*]:=laz1[i];
       tree[i*+]:=laz1[i];
       laz1[i*]:=laz1[i];
       laz1[i*+]:=laz1[i];
       laz1[i]:=-;
       laz2[i]:=;
     end;
     if laz2[i]<> then
     begin
       inc(tree[i*],laz2[i]);
       inc(tree[i*+],laz2[i]);
       if laz1[i*]<>- then inc(laz1[i*],laz2[i])
       else inc(laz2[i*],laz2[i]);
       if laz1[i*+]<>- then inc(laz1[i*+],laz2[i])
       else inc(laz2[i*+],laz2[i]);
       laz2[i]:=;
     end;
   end;

 procedure dfs1(x:longint);
   var i,y:longint;
   begin
     i:=p[x];
     size[x]:=;
     while i<> do
     begin
       y:=w[i].po;
       if fa[x]<>y then
       begin
         fp[y]:=w[i].num;
         fa[y]:=x;
         d[y]:=d[x]+;
         dfs1(y);
         size[x]:=size[x]+size[y];
       end;
       i:=w[i].next;
     end;
   end;

 procedure dfs2(x:longint);
   var i,y,q:longint;
   begin
     i:=p[x];
     q:=;
     while i<> do
     begin
       if fa[w[i].po]=x then
         if size[w[q].po]<size[w[i].po] then q:=i;
       i:=w[i].next;
     end;
     if q= then exit;
     top[w[q].po]:=top[x];
     son[x]:=w[q].num;
     inc(t);
     c[t]:=w[q].num;
     b[w[q].num]:=t;
     dfs2(w[q].po);
     i:=p[x];
     while i<> do
     begin
       y:=w[i].po;
       if (i<>q) and (fa[y]=x) then
       begin
         inc(t);
         c[t]:=w[i].num;
         b[w[i].num]:=t;
         top[y]:=y;
         dfs2(y);
       end;
       i:=w[i].next;
     end;
   end;

 procedure build(i,l,r:longint);
   var m:longint;
   begin
     laz1[i]:=-;
     laz2[i]:=;
     if l=r then tree[i]:=a[c[l]]
     else begin
       m:=(l+r) shr ;
       build(i*,l,m);
       build(i*+,m+,r);
       tree[i]:=max(tree[i*],tree[i*+]);
     end;
   end;

 procedure change(i,l,r,x,y,z:longint);
   var m:longint;
   begin
     if x>y then exit;
     if (x<=l) and (y>=r) then
     begin
       laz1[i]:=z;
       tree[i]:=z;
       laz2[i]:=;
     end
     else begin
       push(i);
       m:=(l+r) shr ;
       if x<=m then change(i*,l,m,x,y,z);
       if y>m then change(i*+,m+,r,x,y,z);
       tree[i]:=max(tree[i*],tree[i*+]);
     end;
   end;

 procedure fadd(i,l,r,x,y:longint);
   var m:longint;
   begin
     if x>y then exit;
     if (x<=l) and (y>=r) then
     begin
       if laz1[i]<>- then inc(laz1[i],z)
       else inc(laz2[i],z);
       inc(tree[i],z);
     end
     else begin
       push(i);
       m:=(l+r) shr ;
       if x<=m then fadd(i*,l,m,x,y);
       if y>m then fadd(i*+,m+,r,x,y);
       tree[i]:=max(tree[i*],tree[i*+]);
     end;
   end;

 function getans(i,l,r,x,y:longint):longint;
   var m,s:longint;
   begin
     if x>y then exit();
     if (x<=l) and (y>=r) then exit(tree[i])
     else begin
       push(i);
       m:=(l+r) shr ;
       s:=;
       if x<=m then s:=getans(i*,l,m,x,y);
       if y>m then s:=max(s,getans(i*+,m+,r,x,y));
       exit(s);
     end;
   end;

 procedure cover(x,y:longint);
   var f1,f2:longint;
   begin
     f1:=top[x];
     f2:=top[y];
     while f1<>f2 do
     begin
       if d[f1]>=d[f2] then
       begin
         change(,,n-,b[fp[f1]],b[fp[x]],z);
         x:=fa[f1];
       end
       else begin
         change(,,n-,b[fp[f2]],b[fp[y]],z);
         y:=fa[f2];
       end;
       f1:=top[x];
       f2:=top[y];
     end;
     if x=y then exit
     else if b[fp[x]]>b[fp[y]] then swap(x,y);
     change(,,n-,b[son[x]],b[fp[y]],z);
   end;

 procedure add(x,y:longint);
   var f1,f2:longint;
   begin
     f1:=top[x];
     f2:=top[y];
     while f1<>f2 do
     begin
       if d[f1]>=d[f2] then
       begin
         fadd(,,n-,b[fp[f1]],b[fp[x]]);
         x:=fa[f1];
       end
       else begin
         fadd(,,n-,b[fp[f2]],b[fp[y]]);
         y:=fa[f2];
       end;
       f1:=top[x];
       f2:=top[y];
     end;
     if x=y then exit
     else if b[fp[x]]>b[fp[y]] then swap(x,y);
     fadd(,,n-,b[son[x]],b[fp[y]]);
   end;

 function ask(x,y:longint):longint;
   var s,f1,f2:longint;
   begin
     s:=;
     f1:=top[x];
     f2:=top[y];
     while f1<>f2 do
     begin
       if d[f1]>=d[f2] then
       begin
         s:=max(s,getans(,,n-,b[fp[f1]],b[fp[x]]));
         x:=fa[f1];
       end
       else begin
         s:=max(s,getans(,,n-,b[fp[f2]],b[fp[y]]));
         y:=fa[f2];
       end;
       f1:=top[x];
       f2:=top[y];
     end;
     if x=y then exit(s)
     else if b[fp[x]]>b[fp[y]] then swap(x,y);
     s:=max(s,getans(,,n-,b[son[x]],b[fp[y]]));
     exit(s);
   end;

 begin
   readln(n);
   for i:= to n- do
   begin
     readln(x,y,a[i]);
     add(x,y,i);
     add(y,x,i);
   end;
   t:=;
   dfs1();
   top[]:=;
   dfs2();
   while true do
   begin
     read(ch);
     s:='';
     while ch<>' ' do
     begin
       s:=s+ch;
       if s='Stop' then halt;
       read(ch);
     end;
     read(x,y);
     if s='Max' then
       writeln(ask(x,y))
     else if s='Change' then
       change(,,n-,b[x],b[x],y)
     else if s='Cover' then
     begin
       read(z);
       cover(x,y);
     end
     else if s='Add' then
     begin
       read(z);
       add(x,y);
     end;
     readln;
   end;
 end.