NOIP复习-001——快速排序

var a:array[1..1000]of longint;
n,i,j:longint;
procedure qp(l,r:longint);
var m,i,j,t:longint;
begin
i:=l;
j:=r;
m:=a[(i+j)div 2];
repeat
while a[i]>m do inc(i);
while a[j]<m do dec(j);
if i<=j then
begin
t:=a[i];
a[i]:=a[j];
a[j]:=t;
inc(i);
dec(j);
end;
until i>j;
if i<r then qp(i,r);
if j>l then qp(l,j);
end;
begin
readln(n);
for i:=1 to n do
read(a[i]);
qp(1,n);
for i:=1 to n do
write(a[i],' ');
end.