Scala algorithm: Add numbers without using addition (plus sign)
Add two numbers without using addition (+ sign). Can be done with bitwise operations.
For example, 5 + 3 is 8; in binary it is 101 + 011 = 1000.
Test cases in Scala
Algorithm in Scala
20 lines of Scala (compatible versions 2.13 & 3.0), showing how concise Scala can be!
Recommended to draw out a table of additions: from the table you learn that binary addition uses the same principles of carrying a number when the base (in this case 2) is exceeded (eg 0b1 + 0b1 = 0b10, and 0b11 + 0b01 = 0b10 + 0b10 = 0b100).
The key tasks here are to add up the number bit-wise, while considering the possibility of a carry-number. (this is © from www.scala-algorithms.com)
Scala concepts & Hints
Def Inside Def
A great aspect of Scala is being able to declare functions inside functions, making it possible to reduce repetition.
It is also frequently used in combination with Tail Recursion.
Stack safety is present where a function cannot crash due to overflowing the limit of number of recursive calls.
This function will work for n = 5, but will not work for n = 2000 (crash with java.lang.StackOverflowError) - however there is a way to fix it :-)
In Scala Algorithms, we try to write the algorithms in a stack-safe way, where possible, so that when you use the algorithms, they will not crash on large inputs. However, stack-safe implementations are often more complex, and in some cases, overly complex, for the task at hand.
In Scala, tail recursion enables you to rewrite a mutable structure such as a while-loop, into an immutable algorithm.