1) For those who get WA 1 mb helps :
with
while (!cin.eof()) char c = cin.get();
i had WA 1
with
char t[10000];
cin.getline(t, 1000);
i had WA 9 !

2)
the problem says that the length of input is no more than 10000 characters

but this code
...
char t[10000];
cin.getline(t, 10000)
...
get WA9
this :
char t[20000];
cin.getline(t, 20000);
get AC

Strange, isn't it?

Yes，It's very strange!

-----------
char t[10001];
cin.getline(t,10000,'\n');
----------
I got WA9.

-----------
char t[10001];
cin.getline(t,10001,'\n');
----------
I got AC!

1. Maybe you didn't add a '\0' at the end of string when reading by chars.
2. For maxlen=10000, array must be at least as big as 10001!