OJ Board

I think there is a little tric with the prob.
if anyone just findout the number of power of two and
five and deduct them till that number from 2
and do mod in every section that make the solve faster.

i think you should divide with 10000 instead of 10

-- Post removed by Observer --

-- Post removed by Observer --

why my answer always gets PE?
[cpp]
#include <iostream.h>
#include <stdio.h>

int main()
{
long n,i,b;
while (cin >> n)
{
b = 1;
for (i = 1;i <= n;i++)
{
b *= i;
while (!(b % 10))
b /= 10;
b %= 100000;
}
while (!(b % 10))
b /= 10;
b %= 10;
printf ("%5ld -> %ld\n",n,b);
}
return 0;
}[/cpp]

I got PE as well...

I'm quite sure that the judge is wrong on this issue (Look at the statistics!)

Just to remind you guys that are trying to solve this problem: you don't need to calculate the entire number! It would be so big that it would not fit into any data type, and you don't need to implement "string array" or a "big int" class..

Since you only want the final digit, why bother with the rest of them?

I hope this helps someone!

Just factor 2 and factor 5 make 0s in the result and obviously factor 2 is more than factor 5 in the factorial.
Think about the last digits which don't contain 2 or 5s then add num(2) - num(5) 2s to the result and get the answer.

num(n) how many factor ns in the factorial.

hope it can help

good luck

It's impossible!
I got AC with same loop
take a look Strange?!

Hi, i am getting WA in this problem, i tried several inputs and it seems okay, I tried to precalculate the last digit, what is wrong with my code ???
I submitted it several times with different modification and every time its WA. Can anyone help me to find me my bug or with some i/o for which this code fails ?

Thanks in advance ...

I 've tried several ways and it is still WA. Any critical I/O for which my above program fails will be a great help. Can you help me to find me my bugs (coz i 've failed to find )??? Thanks anyway.

EDIT: ACC now

i found the run time is too long.
this is my code:
#include "iostream.h"
#include "stdio.h"

int main(int argc, char* argv[])
{
long n;
long sum;
long i;
while(cin>>n)
{
sum=1;
for(i=n;i>0;i--)
{
sum*=i;
}
while(sum>0)
{
if(sum%10!=0)
{
cout<<sum%10<<endl;
sum/=10;
break;
}
else
sum/=10;
}
}
return 0;
}

Use an array to precalculate values upto 10000.

Hi athlon19831

Have you checked your sample input and output. your this part is totally wrong. (when you multiply the value at that time it exceed the integer range) Try to solve this problem in another approch.

Thanks
MAP.