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[0..1000010] of node;
    anc:array[0..500005,0..20] of longint;
    dep,fa,p:array[0..500005] of longint;
    v:array[0..500005] 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<>0 do
    begin
      y:=w[i].po;
      if not v[y] then
      begin
        fa[y]:=x;
        dep[y]:=dep[x]+1;
        dfs(y);
      end;
      i:=w[i].next;
    end;
  end;

procedure prework;
  var i,j,h:longint;
  begin
    fillchar(anc,sizeof(anc),255);
    h:=0;
    for i:=1 to n do
    begin
      anc[i,0]:=fa[i];
      if dep[i]>h then h:=dep[i];
    end;
    t:=trunc(ln(h)/ln(2));
    for j:=1 to t do
      for i:=1 to n do
      begin
        b:=anc[i,j-1];
        if anc[b,j-1]<>-1 then anc[i,j]:=anc[b,j-1];
      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(2));
      for i:=p downto 0 do
        if dep[x]-1 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(2));
    for i:=p downto 0 do
      if (anc[x,i]<>-1) 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:=1 to n-1 do
  begin
    readln(x,y);
    add(x,y);
    add(y,x);
  end;
  fa[1]:=-1;
  dfs(1);
  prework;
  for i:=1 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]-2*dep[c]+dep[c]+dep[x]-2*dep[lca(x,c)])
    else if a=c then
      writeln(b,' ',dep[x]+dep[z]-2*dep[b]+dep[b]+dep[y]-2*dep[lca(y,b)])
    else if b=c then
      writeln(a,' ',dep[x]+dep[y]-2*dep[a]+dep[a]+dep[z]-2*dep[lca(z,a)])
  end;
end.