bzoj1832

其实这道题是和bzoj1787一样的
但我用bzoj1787MLE了，于是正好练一下树上倍增

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

 var w:array[..] of node;
     anc:array[..,..] of longint;
     dep,fa,p:array[..] of longint;
     v:array[..] of boolean;
     t,len,x,y,z,a,b,c,i,n,m:longint;

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

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

 procedure dfs(x:longint);
   var i,y:longint;
   begin
     v[x]:=true;
     i:=p[x];
     while i<> do
     begin
       y:=w[i].po;
       if not v[y] then
       begin
         fa[y]:=x;
         dep[y]:=dep[x]+;
         dfs(y);
       end;
       i:=w[i].next;
     end;
   end;

 procedure prework;
   var i,j,h:longint;
   begin
     fillchar(anc,sizeof(anc),);
     h:=;
     for i:= to n do
     begin
       anc[i,]:=fa[i];
       if dep[i]>h then h:=dep[i];
     end;
     t:=trunc(ln(h)/ln());
     for j:= to t do
       for i:= to n do
       begin
         b:=anc[i,j-];
         if anc[b,j-]<>- then anc[i,j]:=anc[b,j-];
       end;
   end;

 function lca(x,y:longint):longint;
   var i,p:longint;
   begin
     if dep[x]<dep[y] then swap(x,y);
     if dep[x]<>dep[y] then
     begin
       p:=trunc(ln(dep[x])/ln());
       for i:=p downto  do
         if dep[x]- shl i>=dep[y] then
         begin
           x:=anc[x,i];
           if dep[x]=dep[y] then break;
         end;
     end;

     if x=y then exit(y);
     p:=trunc(ln(dep[x])/ln());
     for i:=p downto  do
       if (anc[x,i]<>-) and (anc[x,i]<>anc[y,i]) then
       begin
         x:=anc[x,i];
         y:=anc[y,i];
       end;
     exit(fa[x]);
   end;

  begin
   readln(n,m);
   for i:= to n- do
   begin
     readln(x,y);
     add(x,y);
     add(y,x);
   end;
   fa[]:=-;
   dfs();
   prework;
   for i:= to m do
   begin
     readln(x,y,z);
     a:=lca(x,y);
     b:=lca(x,z);
     c:=lca(y,z);
     if a=b then
       writeln(c,' ',dep[y]+dep[z]-*dep[c]+dep[c]+dep[x]-*dep[lca(x,c)])
     else if a=c then
       writeln(b,' ',dep[x]+dep[z]-*dep[b]+dep[b]+dep[y]-*dep[lca(y,b)])
     else if b=c then
       writeln(a,' ',dep[x]+dep[y]-*dep[a]+dep[a]+dep[z]-*dep[lca(z,a)])
   end;
 end.