pku1330 Nearest Common Ancestors

rogram pku1330(input,output);
type
node    = ^link;
link    = record
goal : longint;
next : node;
end;
var
tree       : array[0..31000] of node;
eurl       : array[0..30000] of longint;
depth   : array[0..30000] of longint;
pos       : array[0..31000] of longint;
f       : array[0..21000,0..20] of longint;
v       : array[0..11000] of boolean;
root       : longint;
n,tot   : longint;
i,cases : longint;
function max(aa,bb: longint ):longint;
begin
if aa>bb then
exit(aa);
exit(bb);
end; { max }
function min(aa,bb : longint ):longint;
begin
if aa<bb then
exit(aa);
exit(bb);
end; { min }
procedure add(xx,yy :longint );
var
tt : node;
begin
new(tt);
tt^.goal:=yy;
tt^.next:=tree[xx];
tree[xx]:=tt;
end; { add }
procedure delete();
var
tt : node;
begin
for i:=1 to n do
while tree[i]<>nil do
begin
tt:=tree[i];
tree[i]:=tt^.next;
dispose(tt);
end;
end; { delete }
procedure init;
var
i,xx,yy : longint;
begin
readln(n);
fillchar(v,sizeof(v),false);
for i:=1 to n-1 do
begin
readln(xx,yy);
add(xx,yy);
v[yy]:=true;
end;
for i:=1 to n do
if not v[i] then
begin
root:=i;
break;
end;
for i:=1 to n do
pos[i]:=-1;
tot:=0;
end; { init }
procedure dfs(now,dep :longint );
var
t : node;
begin
inc(tot);
eurl[tot]:=now;
depth[tot]:=dep;
if pos[now]=-1 then
pos[now]:=tot;
t:=tree[now];
while t<>nil do
begin
dfs(t^.goal,dep+1);
inc(tot);
eurl[tot]:=now;
depth[tot]:=dep;
t:=t^.next;
end;
end; { dfs }
procedure Sparse_Table();
var
i,j : longint;
begin
for i:=1 to tot do
f[i,0]:=i;
for j:=1 to trunc(ln(tot)/ln(2)) do
for i:=1 to tot do
if i+1<<(j-1)>tot then
break
else
begin
if depth[f[i,j-1]]<depth[f[i+1<<(j-1),j-1]] then
f[i,j]:=f[i,j-1]
else
f[i,j]:=f[i+1<<(j-1),j-1];
end;
end; { Sparse_Table }
procedure solve();
var
x,y,t,xx,yy : longint;
begin
readln(x,y);
xx:=pos[x];
yy:=pos[y];
x:=min(xx,yy);
y:=max(xx,yy);
t:=trunc(ln(y-x+1)/ln(2));
if depth[f[x,t]]<depth[f[y-1<<t+1,t]] then
writeln(eurl[f[x,t]])
else
writeln(eurl[f[y-1<<t+1,t]]);
end; { solve }
begin
for i:=1 to 10001 do
tree[i]:=nil;
readln(cases);
while cases>0 do
begin
dec(cases);
delete();
init;
dfs(root,0);
Sparse_Table();
solve();
end;
end.