其实我测试了样例数据，过了样例数据，也测试了某个评论的第二组数据，答案也相同，不过没想通为什么过不了，一个点也不对？求大神指出错误。
program a01;
var
point,k1,k2,n,m,p,i,j,number:longint;
a:array[1..5003] of longint;
begin
read(n,m,p);
fillchar(a,sizeof(a),0);
for i := 1 to m do
begin
read(k1,k2);
if (a[k1]=0) and (a[k2]=0) then
begin
number:=number+1;
a[k1]:=number;
a[k2]:=number;
end;
if a[k1]<>a[k2] then begin
if (a[k1]<>0) and (a[k2]=0) then a[k2]:=a[k1]
else
if (a[k1]=0) and (a[k2]<>0) then a[k1]:=a[k2]
else
if (a[k1]<>0) and (a[k2]<>0) then begin
point:=a[k2];
for j := 1 to n do
if a[j]= point then a[j]:=a[k1];
end;
end;

end;
for i := 1 to p do
begin
read(k1,k2);
if (a[k1]=a[k2]) and (a[k1]<>0) then writeln('yes')
else writeln('no');
end;
end.

难道是代码打得太难看了？全部wa……