Imp thing in Python 3.5

help
#1

I was working on problem from like past day, I got WA in c++ in couple of test cases, as a result I switched to Python 3. 6 and that’s where I found a thing which can give you WA frequently. It is related to large numbers.
For eg:
py print((2001100545* 2001100544)/2)
will print 2.0022016945990984e+18
and doing it modulo with 10**9 + 7 will give 583686608.0.

But if we do so with C++ or python 2x…
it will give 584787011.

See the difference ^^.
In such cases python 2x will returns right answer because it have long type and interpreter automatically decides, which type i.e. int or long is to be used.

1 Like
#2

This is because you did not use the mod correctly. For (nm) , you must do ((n%mod)(m%mod))%mod. You should get the correct answer.

#3

This will only solve problem if there is modulo.
What about difference betweeen 2.0022016945990984e+18 and 2002201694599098240.
Obviously, print(2002201694599098240==2.0022016945990984e+18) will return False

1 Like
#4

You are wrong. ‘/’ in python 3 does normal division and not integer division. For integer division you have to use ‘//’.

6 Likes
#5

/ and // matters :stuck_out_tongue:

4 Likes
#6

2.00e+18 something like this is called scientific notation
it showing u how the number is stored
it wont return false coz while comparing it will compare original values
as far as to solve the prob do as said by @anon70990627
py do mind data type. Hence u can store larges values
but c++ does min. so u need to take care of it

#7

Thanks for sharing.
It was very helpful for me

#8

thank u so much for your help…