10323

zhangl · Post by **zhangl** » Tue Nov 05, 2002 2:31 am

why die i got wrong?
who can help me?

turingcomplete · Post by **turingcomplete** » Tue Nov 05, 2002 5:30 am

To the problem setter: thanks for wasting an hour of time. If you want to make up some function then don't call it factorial, as it's really confusing to those of us who know that factorial is only defined for 0+.

Ghost77 dimen · Post by **Ghost77 dimen** » Thu Nov 07, 2002 9:52 am

Come on, turingcomplete.

The title is so clear that it play a trick on us.

Didn't you think for a while why it said that " You must be kidding."?

ec3_limz · Post by **ec3_limz** » Wed Feb 05, 2003 5:17 pm

Why WA?

[cpp]#include <iostream.h>
typedef unsigned long long ULLT;

int main() {
const ULLT UNDER = 10000LL, OVER = 6227020800LL;
ULLT limit, fact, i;

while (cin >> limit) {
fact = 1;
for (i = 1; i <= limit; i++) {
fact *= i;
if (fact > OVER) {
cout << "Overflow!\n";
break;
}
}

if (fact <= OVER) {
if (fact < UNDER)
cout << "Underflow!\n";
else
cout << fact << '\n';
}
}

return 0;
}[/cpp]

angga888 · Post by **angga888** » Thu Feb 06, 2003 6:25 am

The problem doesn't state the minimum input, so you must handle negative factorial, like : -1!, -2!, -3!, ...
To find the answer of that problem, just simulate this formula :
(n-1) ! = n ! / n

Good Luck !

knightmare · Post by **knightmare** » Fri Feb 07, 2003 1:55 am

For negative numbers it's always underflow or overflow (depends on whether the number is even or odd).

This problem is completely stupid (mathematically incorrect), as you can read on this thread:

http://acm.uva.es/board/viewtopic.php?t=803

You can start flaming me for posting the "solution" here, I don't care... People shouldn't be supposed to guess, only to think about logical things.

Red Scorpion · Post by **Red Scorpion** » Fri Feb 07, 2003 7:54 am

How if the input is :
Input :
-1
-2
-3

Ouput:
Overflow
Underflow
Overflow

Is This Right ?
Regards,
RED SCORPION

Red Scorpion · Post by **Red Scorpion** » Fri Feb 07, 2003 12:17 pm

Yes, I Got AC,
when it is a negative number, I look if it is EVEN,
then the output should be Underflow!, else if
it is ODD then the output should be Overflow!

Thanks,
RED SCORPION

angga888 · Post by **angga888** » Fri Feb 07, 2003 12:20 pm

Yes, you're right, Red Scorpion.

And that pattern will repeat again and again (for negative factorial).
However, I still think that negative factorial is undefined.

razibcse · Post by **razibcse** » Fri Feb 21, 2003 8:26 pm

I can't understand how to calculate factorial of negative numbers...if u put n=0 in the formula (n-1)!=n!/n, u get
-1!=0!/0...how is this possible?

pls give some explanation of the process how negative even numbers get Underflow! and odd numbers get Overflow!...

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Razib
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Our lives improve only when we take chances - and the first and most
difficult risk we can take is to be honest with ourselves.[/quote]

Jalal · Post by **Jalal** » Sat Feb 22, 2003 8:34 pm

Yes! no doubt about it!
One of the most stupid problem it is!
As far i know acm is for updating our brain.
Not for damage our topic's with bad theory
just to make a problem ubsolved

VitorRodrigues · Post by **VitorRodrigues** » Wed Apr 16, 2003 7:15 pm

Hisoka and razibcse, you do not have to use any formula to calculate factorial of negative numbers. Jus print "Overflow!" if the number is odd, or "Underflow!" if the number is even.

Good luc

Eric · Post by **Eric** » Thu Apr 17, 2003 6:08 am

I get WA.
I think the problem is :

It used to contain the correct algorithm, but I deleted.

Can anyone help me?

little joey · Post by **little joey** » Thu Apr 17, 2003 7:39 am

Eric: You do Pascal, don't you? PM me your code, and I'll have a look.

Eric · Post by **Eric** » Thu Apr 17, 2003 12:41 pm

I get Accepted now. Thanks Joey.
It is really a careless mistake.

OJ Board

10323 - Factorial! You Must be Kidding!!!

P 10323

Give some explanation