Fast Multiplication Error

[inarvaez]

I can´t seem to understand why I´m getting a wrong answer message. Could someone please enlighten me on this?
Here is my source code, it is written in python 2.6:

n=input("")
if n<=1000:
for i in range(0,n):
inp=raw_input()
x=inp.split()
mult=1
if len(x)==2:
for i in range(0,2):
if len(x[i])<10000:
mult=mult*int(x[i])
print mult

[hendrik]

If you show your code you sould use the Code tags. Especially for Python. The indents matter.
Apart from that in normal case when the code is correct you should rather get TLE than WA. Python is not fast enough for that problem.

[inarvaez]

This is the way I indented it. The time actually doesn´t seem to be a problem in mine, SPOJ tells me it executes in 0.18 seconds. I just wonder if there is something wrong in the code, I´ve tried it a hundred times and have no idea what could be wrong with it.

n=input("")
if n<=1000:
	for i in range(0,n):
		inp=raw_input()
		x=inp.split()
		mult=1
		if len(x)==2:
			for i in range(0,2):
				if len(x[i])<10000:
					mult=mult*int(x[i])
			print mult	

[hendrik]

What if one of the factors has exactly 10000 digits?

[inarvaez]

Oh my god thanks man your a genius. Now it´s sending me the TLE error you said it would say. You were right about the language being too slow.

[hendrik]

... and then just a comment to your code even though it wont help for MUL. It looks a bit complicated.
You could simply do like this.

a,b = map(int,raw_input().split())
print a*b

There are lots of other interessting problems that you can solve with Python. I think it is quite fun to play here. You can learn a lot.

[numerix]

You were right about the language being too slow.

The problem here is not the multiplication itself (python uses Karatsuba multiplication), but the I/O of large numbers. That is really slow in python.

[m_vidhyasagaran]

n=int(input())
if n<=1000:
          for c in range(0,n):
                              a=input()
                              u=a.find(" ",0,len(a))
                              x1=a[0:u]
                              x2=a[u+1:]
                              l1=int(x1)
                              l2=int(x2)
                              if l1<=pow(10,10000):
                                          if(l2<=pow(10,10000)):
                                                                           l3=l1*l2
                                                                           print(l3)
                                                                           c=c+1

I am getting TLE.can any one help me in that.

[hendrik]

Please read the posts in that thread completely. That should give you the answer. And then just a comment to one of your lines of code. The following I found quite strange:

if l1<=pow(10,10000):

Are you sure that this is the best way of checking the size of a number? Think about it. And then ask yourself why you do this. And then for the next post please dont forget the code tags. You know that indentation matters in Python.

[m_vidhyasagaran]

i think line" if l1<=pow(10,10000):" is correct.but i found because of that line"if l1<=pow(10,10000):" i am getting TLE.so can you please give any other alternate for this.

[numerix]

What are you doing, man? Your code is completely broken, full of really silly things.
To multiply two numbers with Python, just read them
[bbone=Python,68]a, b = map(int, raw_input().split())[/bbone]
and print the result:
[bbone=Python,69]print a*b[/bbone]
That's all and works for arbitrary large numbers.

But: What do you think is the reason that there is no AC Python solution for that problem until now?
And: What do you think is the reason that there are only a few AC solutions to tutorial variant TMUL with longer runtime?

To make it short: Multiplication in Python is by far fast enough. Reading the input and converting to int is not so fast, but fast enough.
Converting the result to str (which cannot be avoided - if you print an integer there is also an implicit conversion) for output is veeeery slow and the bottleneck of this problem. You have to do some optimizing on that to get a Python TMUL-solution AC and I'm quite sure that it will not be possible to get a (pure) Python solution AC for problem MUL.

Hint: Go through the Python tutorial and then try some other problems on SPOJ.