multiply numbers (linked lists)

[StOoZ]

First of all , im not looking for a code!!!!!
any suggestions on how to multiply two numbers , where both are represented by a linked list (one digit for each node) , and create a third linked list , which represents the multiplication outcome.

I bet there is a better way to do it than how we do it "by hand" , I mean , the usual way with pencil and paper when you do it like:
111
35
----
555
333
------

and so on...

[johnl]

One option would be to convert the linked lists into their numeric form, do the multiplication, and then build a linked list of the result. Whether or not this is easier or better than the 'old-fashioned' method you described is up to you :)

[soltanis]

Computers multiply numbers in a highly efficient manner, if that's what you're asking. If you want a better way to do it by hand, I would suggest googling for a video called "how chinese multiply" or something like that, which shows a very fast and pretty intuitive method for multiplying numbers with multiple digits that is far superior to the long-handed method taught in elementary school.

[dwhitney67]

First of all , im not looking for a code!!!!!
any suggestions on how to multiply two numbers , where both are represented by a linked list (one digit for each node) , and create a third linked list , which represents the multiplication outcome.

I bet there is a better way to do it than how we do it "by hand" , I mean , the usual way with pencil and paper when you do it like:
111
35
----
555
333
------

and so on...
Construct the number using the digit at each node. Presumably you know the number of nodes beforehand.


value1 = 0;
size = list1.size
node = list1.head

while node is not null
value1 += (node.digit * 10 ^ (size - 1))
node = node.next

// repeat for other list to yield value2

result = value1 * value2


To convert 'result' to a list, you need to deduce the number of digits in the value; then for each digit, starting at the most significant, insert it into the list.

P.S. When defining a list, decide whether you will insert at the tail or at the head. The algorithm/suggestion above assumes that a digit is inserted at the tail.

[nvteighen]

Computers multiply numbers in a highly efficient manner, if that's what you're asking. If you want a better way to do it by hand, I would suggest googling for a video called "how chinese multiply" or something like that, which shows a very fast and pretty intuitive method for multiplying numbers with multiple digits that is far superior to the long-handed method taught in elementary school.
Amazing... http://www.youtube.com/watch?v=sBkdT9N4Y7w