a,b:array[0..5000]of integer;

i,j,max,s:longint;

begin

readln(n);

for i:=1 to n do read(a[i]);

b[n]:=1;

a[0]:=10000;

for i:=1 to n do

for j:=i-1 downto 0 do

begin

if (a[j]>a[i])and(b[i]<b[j]+1) then b[i]:=b[j]+1;

if b[i]>max then max:=b[i];

write(max,' ');

writeln(s);

end.

除了b[n]，其他b数组都没赋值？那你要如何进行这项比较b[i]<b[j]+1？