How to resolve the algorithm Ethiopian multiplication step by step in the Smalltalk programming language

Published on 12 May 2024 09:40 PM
#Smalltalk

How to resolve the algorithm Ethiopian multiplication step by step in the Smalltalk programming language

Table of Contents

Problem Statement

Ethiopian multiplication is a method of multiplying integers using only addition, doubling, and halving.

Method:

For example:   17 × 34 Halving the first column: Doubling the second column: Strike-out rows whose first cell is even: Sum the remaining numbers in the right-hand column: So 17 multiplied by 34, by the Ethiopian method is 578.

The task is to define three named functions/methods/procedures/subroutines:

Use these functions to create a function that does Ethiopian multiplication.

Let's start with the solution:

Step by Step solution about How to resolve the algorithm Ethiopian multiplication step by step in the Smalltalk programming language

Source code in the smalltalk programming language

Number extend [
  double [ ^ self * 2 ]
  halve  [ ^ self // 2 ]
  ethiopianMultiplyBy: aNumber withTutor: tutor [
    |result multiplier multiplicand|
    multiplier := self.
    multiplicand := aNumber.
    tutor ifTrue: [ ('ethiopian multiplication of %1 and %2' % 
                      { multiplier. multiplicand }) displayNl ].
    result := 0.
    [ multiplier >= 1 ]
      whileTrue: [
        multiplier even ifFalse: [
                           result := result + multiplicand.
                           tutor ifTrue: [
                              ('%1, %2 kept' % { multiplier. multiplicand })
                                displayNl
                           ]       
                        ]
                        ifTrue: [
                           tutor ifTrue: [
                             ('%1, %2 struck' % { multiplier. multiplicand })
			       displayNl
                           ]
                        ].
        multiplier := multiplier halve.
        multiplicand := multiplicand double.
      ].
    ^result
  ]
  ethiopianMultiplyBy: aNumber [ ^ self ethiopianMultiplyBy: aNumber withTutor: false ]
].

(17 ethiopianMultiplyBy: 34 withTutor: true) displayNl.

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