NKTREE - Cây nhị phân tìm kiếm
Tác giả: happyboy99x
Ngôn ngữ: Pascal
var min, max, pre, now: longint;
BEGIN
read(pre); min := low(longint); max := high(longint);
while not seekEOF do
begin
read(now);
if(now = pre) or (now < min) or (now > max) then
begin
writeln('NO');
halt;
end;
if(now < pre) then max := pre - 1
else min := pre + 1;
pre := now;
end;
writeln('YES');
END.