Solutions for https://www.gotealeaf.com/books/ruby/read/intro_exercises

exercises.rb

puts "Solution to 1:"
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10].each { |num| puts num}

puts
puts "Solution to 2:"
[1, 2, 3, 4, 5, 6, 7, 8, 9, 10].each { |num| puts num if num > 5 }

puts
puts "Solution to 3:"
odds = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10].select {|num| num % 2 == 1 }
puts odds

puts
puts "Solution to 4:"
arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
arr.push(11)
arr.unshift(0)
puts arr

puts
puts "Solution to 5:"
arr.pop()
arr.push(3)
puts arr

puts
puts "Solution to 6:"
puts arr.uniq

puts
puts "Solution to 7:"
puts "Array is a sequential data structure where elements are accessed via indicies."
puts "Hash is an associate data structure where values are accessed via keys."

puts
puts "Solution to 8:"
old_style_hash = {:name => 'Tom', :age => 42, "non-symbol-key" => 1}
puts old_style_hash
new_style_hash = {name: 'Tom', age: 42, "non-symbol-key" => 1}
puts new_style_hash

puts
puts "Solution to 9:"
h = {a:1, b:2, c:3, d:4}
puts h[:b]
h[:e] = 5
h.delete_if { |key, val| val < 3.5 }
puts h

puts
puts "Solution to 10:"
# gotcha: must surround hash literal with parentheses otherwise syntax error
puts ({key: [1, 2, 3]})
puts [{key1: 1}, {key2: 2}]

puts
puts "Solution to 11:"
puts "ruby-doc.org seems okay to me."

puts
puts "Solution to 12:"
keys = [:email, :address, :phone]
contact_data = [["joe@email.com", "123 Main st.", "555-123-4567"],
                ["sally@email.com", "404 Not Found Dr.", "123-234-3454"]]
contacts = {"Joe Smith" => {}, "Sally Johnson" => {}}

contacts.keys.each do |name|
    first_name = name.split[0].downcase
    contact_data.each do |data|
        if data[0].include?(first_name)
            contacts[name] = Hash[keys.zip(data)]
            break
        end
    end
end
puts contacts

puts
puts "Solution to 13:"
puts "Joe's email is #{contacts["Joe Smith"][:email]}"
puts "Sally's phone number is #{contacts["Sally Johnson"][:phone]}"

puts
puts "Solution to 14:"
puts "Already done in solution to 12"

puts
puts "Solution to 15:"
arr = ['snow', 'winter', 'ice', 'slippery', 'salted roads', 'white trees']
arr.delete_if { |word| word.start_with?('s') }
puts arr
puts
arr = ['snow', 'winter', 'ice', 'slippery', 'salted roads', 'white trees']
arr.delete_if { |word| word.start_with?('s', 'w') }
puts arr

puts
puts "Solution to 16:"
a = ['white snow', 'winter wonderland', 'melting ice',
     'slippery sidewalk', 'salted roads', 'white trees']
puts a.map { |w| w.split }.flatten

puts
puts "Solution to 17:"
puts "These hashes are the same!"