a数组开到qword，范围加到100000
```pas
uses math;
var n,k,s,m,l,r:qword;
i:longint;
a:array[1..100000] of qword;
x:extended;
function pd(x:longint):boolean;
var t:longint;
s:qword;
begin
s:=0;
for t:=1 to n do
s:=s+a[t] div x;
exit(s>=k);
end;
begin
readln(n,k);
r:=0;
for i:=1 to n do
begin
readln(x);
a[i]:=trunc(x*100);
end;
for i:=1 to n do
s:=s+a[i];
if (s<k) then begin writeln('0.00'); halt; end;
if (s=k) then begin writeln('1.00'); halt; end;
l:=0;
r:=10000000000000;
repeat
m:=(l+r) div 2;
if pd(m) then l:=m+1 else r:=m-1;
until l>r;
writeln(r/100:0:2);
end.
```
by 彭骐飞 @ 2017-05-01 12:39:11