路径压缩版：var a:array[1..100]of longint;
n,m,p,i,x,y,xx,yy:longint;
begin
readln(n,p);
for i:=1 to p do
a[i]:=i;
for i:=1 to n do
begin
readln(x,y);
a[x]:=a[y];
end;
readln(m);
for i:=1 to m do
begin
readln(x,y);
xx:=x;
while a[xx]<>xx do
begin
a[xx]:=a[a[xx]];
xx:=a[xx];
end;
a[x]:=xx;
yy:=y;
while a[yy]<>yy do
begin
a[yy]:=a[a[yy]];
yy:=a[yy];
end;
a[y]:=yy;
if a[y]=a[x] then
writeln('yes')
else
writeln('no');
end;
end.

楼上版本除了路径压缩以外，还可以越级查询，能防**，为最快速非递归版！！！

竟然被和*了？
就是我是你爸而且你是我爸。

楼上全是错的
这个才是对的
var a:array[1..1000]of longint;
i,r,m,n,x,y:longint;
function father(o:longint):longint;
begin
if a[o]<>o then
a[o]:=father(a[o]);
exit(a[o]);
end;
begin
readln(r,m,n);
for i:=1 to r do
a[i]:=i;
for i:=1 to m do
begin
readln(x,y);
a[father(x)]:=a[y];
end;
for i:=1 to n do
begin
readln(x,y);
if father(x)=father(y) then
writeln('Y')
else
writeln('N');
end;
end.

最快的
var a:array[1..1000]of longint;
i,r,m,n,x,y:longint;
function father(o:longint):longint;
begin
if a[o]<>o then
a[o]:=father(a[o]);
exit(a[o]);
end;
begin
readln(r,m,n);
for i:=1 to r do
a[i]:=i;
for i:=1 to m do
begin
readln(x,y);
a[father(x)]:=father(y);
end;
for i:=1 to n do
begin
readln(x,y);
if father(x)=father(y) then
writeln('Y')
else
writeln('N');
end;
end.