Question

I want to find a multiplication of two numbers in Java recursively with using only Addition, Subtraction and Comparison. So, I googled and I found Egyptian Algorithm that meets the question requirement.

However, I’m not sure how to find the multiplication result after we reach the base case.

Example:

13 x  30

1  -- 30

2  -- 60

4  -- 120

8  -- 240 //we stop here because the double of 8 is larger than 13

To find the result we add the numbers from the left column that equals 13 which they are 1+4+8 and on the other hand we add its opposite numbers from the right column which they are 30+120+240 = 390 which is the result.

But now how to do last part programatically ? how to check which numbers to add? I hope you guys get my point. Hints only needed.

Answer 1

Okay, I did it using Brute Force Algorithm. It’s a BigO-(n) though. I’m sure there is more efficient way to implement it. For now. I’m settling with this.

Thanks guys!