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#!/usr/bin/ruby -w
# ch-2.rb
# https://theweeklychallenge.org/blog/perl-weekly-challenge-146/
#
# ## Task 2 > Curious Fraction Tree
# =================================
#
# Consider the following `Curious Fraction Tree`:
#
# ```
# __________1/1__________
# / \
# ___1/2___ ___2/1___
# / \ / \
# 1/3 3/2 2/3 3/1
# / \ / \ / \ / \
# 1/4 4/3 3/5 5/2 2/5 5/3 3/4 4/1
# ```
#
# You are given a fraction, member of the tree created similar to the above
# sample.
#
# Write a script to find out the parent and grandparent of the given member.
#
# **Example 1:**
#
# ```
# Input: $member = '3/5';
# Output: parent = '3/2' and grandparent = '1/2'
# ```
#
# **Example 2:**
#
# ```
# Input: $member = '4/3';
# Output: parent = '1/3' and grandparent = '1/2'
# ```
################################################################################
# PWC Solution #################################################################
################################################################################
def get_curious_parent(member)
num, den = member.split(%r{/}, 2).map(&:to_i)
val = num.to_f / den.to_f
return nil unless val != 1.0
return "#{num - den}/#{den}" unless val < 1
return "#{num}/#{den - num}" unless val > 1
end
def get_curious_tree(member)
parents = []
child = member
until child.nil?
parents.push child
child = get_curious_parent(child)
end
parents
end
def get_curious_generations(tree, generations = 2)
return [tree[1]] unless tree.length > 2
tree.slice(1, generations)
end
################################################################################
# Utilities ####################################################################
################################################################################
def color_str(color, str)
colors = {
green: "\e[32m",
red: "\e[31m",
reset: "\e[0m",
yellow: "\e[33m"
}
colors[color] + str + colors[:reset]
end
def format_results(tree, results = '')
tree.each_with_index do |member, idx|
length = tree.length
results += color_str(:yellow, 'parent') unless idx > 0
results += color_str(:yellow, 'great-' * (idx - 1)) unless idx < 2
results += color_str(:yellow, 'grandparent') unless idx < 1
results += ' = ' + color_str(:green, member)
results = length == 2 && idx.zero? ? results + ' and ' : results
results = idx == length - 2 && length != 2 ? results + ', and ' : results
results = length > 2 && idx < length - 2 ? results + ', ' : results
end
results
end
def assert_root(tree)
last = tree[-1]
last != '1/1' && color_str(:yellow, 'Curious fraction tree rooted at ') +
color_str(:red, last) +
color_str(:yellow, ' and not at ') +
color_str(:green, '1/1')
end
################################################################################
# Main #########################################################################
################################################################################
prompt =
'Enter a fraction (i.e.: "' +
color_str(:green, '3/5') +
'") or type "' +
color_str(:yellow, 'exit') +
'" to quit /> '
more_prompt =
'Enter "' +
color_str(:yellow, 'more') +
'" to see more details, or enter a fraction (i.e.: "' +
color_str(:green, '3/5') +
'") to continue /> '
banner = 'A Curious Fraction Tree'
puts color_str(:yellow, banner)
puts color_str(:yellow, '=' * banner.length)
current_tree = nil
generations = nil
asserted_root = nil
print prompt
loop do
input = gets.chomp
input.strip!
case input
when %r{\A1\/1\z}
puts color_str(:green, input) + ' is root.'
print prompt
when %r{\A\d+\/\d+\z}
current_tree = get_curious_tree(input)
generations = get_curious_generations(current_tree)
asserted_root = assert_root(current_tree)
puts format_results(generations)
print more_prompt
when /\Amore\z/i
tree = current_tree.slice(1, current_tree.size - 1)
puts format_results(tree)
puts asserted_root if asserted_root
current_tree = nil
generations = nil
asserted_root = nil
print prompt
when /exit|quit|q/i
puts color_str(:yellow, 'Goodbye.')
exit
else puts "I don't understand #{color_str(:yellow, input)}"
end
end
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