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# dhoangk07's solution

## to Wordy in the Ruby Track

Published at Oct 21 2018 · 0 comments
Instructions
Test suite
Solution

#### Note:

This exercise has changed since this solution was written.

Parse and evaluate simple math word problems returning the answer as an integer.

What is 5 plus 13?

Evaluates to 18.

Handle large numbers and negative numbers.

## Iteration 2 β Subtraction, Multiplication and Division

Now, perform the other three operations.

What is 7 minus 5?

2

What is 6 multiplied by 4?

24

What is 25 divided by 5?

5

## Iteration 3 β Multiple Operations

Handle a set of operations, in sequence.

Since these are verbal word problems, evaluate the expression from left-to-right, ignoring the typical order of operations.

What is 5 plus 13 plus 6?

24

What is 3 plus 2 multiplied by 3?

15 (i.e. not 9)

## Bonus β Exponentials

If you'd like, handle exponentials.

What is 2 raised to the 5th power?

32

For installation and learning resources, refer to the Ruby resources page.

For running the tests provided, you will need the Minitest gem. Open a terminal window and run the following command to install minitest:

``````gem install minitest
``````

If you would like color output, you can `require 'minitest/pride'` in the test file, or note the alternative instruction, below, for running the test file.

Run the tests from the exercise directory using the following command:

``````ruby wordy_test.rb
``````

To include color from the command line:

``````ruby -r minitest/pride wordy_test.rb
``````

## Source

Inspired by one of the generated questions in the Extreme Startup game. https://github.com/rchatley/extreme_startup

## Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

### wordy_test.rb

``````require 'minitest/autorun'
require_relative 'wordy'

# Common test data version: 1.1.0 df75482
class WordyTest < Minitest::Test
# skip
problem = WordProblem.new("What is 1 plus 1?")
end

skip
problem = WordProblem.new("What is 53 plus 2?")
end

skip
problem = WordProblem.new("What is -1 plus -10?")
end

skip
problem = WordProblem.new("What is 123 plus 45678?")
end

def test_subtraction
skip
problem = WordProblem.new("What is 4 minus -12?")
end

def test_multiplication
skip
problem = WordProblem.new("What is -3 multiplied by 25?")
end

def test_division
skip
problem = WordProblem.new("What is 33 divided by -3?")
end

skip
problem = WordProblem.new("What is 1 plus 1 plus 1?")
end

skip
problem = WordProblem.new("What is 1 plus 5 minus -2?")
end

def test_multiple_subtraction
skip
problem = WordProblem.new("What is 20 minus 4 minus 13?")
end

skip
problem = WordProblem.new("What is 17 minus 6 plus 3?")
end

def test_multiple_multiplication
skip
problem = WordProblem.new("What is 2 multiplied by -2 multiplied by 3?")
end

skip
problem = WordProblem.new("What is -3 plus 7 multiplied by -2?")
message = "You should ignore order of precedence. -3 + 7 * -2 = -8, not #{problem.answer}"
end

def test_multiple_division
skip
problem = WordProblem.new("What is -12 divided by 2 divided by -3?")
end

def test_unknown_operation
skip
problem = WordProblem.new("What is 52 cubed?")
assert_raises(ArgumentError) do
end
end

def test_non_math_question
skip
problem = WordProblem.new("Who is the President of the United States?")
assert_raises(ArgumentError) do
end
end
end``````
``````require 'byebug'
class WordProblem
def initialize(string)
@string = string
end

result = []
arrays = @string.gsub!('?', '').split(' ')
switch_items = switch_element(arrays)
raise ArgumentError if switch_items.length < 3
index = 3
final = []
length = switch_items.length
while index < length
first = three_element(switch_items[0..2])
result << first
remain_array = remain_array(switch_items, switch_items[0..2])
switch_items = []
switch_items << [result, remain_array ].flatten
length = switch_items.flatten.length
index += 1
end
return three_element(switch_items.flatten)
end

def remain_array(exist_array, _minus_array)
index = exist_array.index(_minus_array.first)
length = _minus_array.length
exist_array.slice!(index, length)
exist_array
end

def switch_element(array)
result = []
array.each do |element|
if element.scan(/^\-?[0-9]+\$/).size == 1
result << element
elsif element == 'plus'
result << "+"
elsif element == 'minus'
result << "-"
elsif element == 'multiplied'
result << "*"
elsif element == 'divided'
result << "/"
end
end
result
end

def three_element(array)
handle_simple_expression(array[0], array[1], array[2])
end

def handle_simple_expression(operand_1, operator, operand_2)
if operator == 0 && operand_2 == 0
return operand_1
else
case operator
when '*'
operand_1.to_i * operand_2.to_i
when '+'
operand_1.to_i + operand_2.to_i
when '/'
operand_1.to_i / operand_2.to_i
when '-'
operand_1.to_i - operand_2.to_i
end
end
end
end

puts WordProblem.new("What is 33 divided by -3?").answer``````

### What can you learn from this solution?

A huge amount can be learned from reading other peopleβs code. This is why we wanted to give exercism users the option of making their solutions public.

Here are some questions to help you reflect on this solution and learn the most from it.

• What compromises have been made?