Solutions day1-day3

mark/day1/example.txt

@@ -0,0 +1,11 @@
+L68
+L30
+R48
+L5
+R60
+L55
+L1
+L99
+R14
+L82
+

mark/day1/part1.rb

@@ -0,0 +1,29 @@
+class RotationDecoder
+  def initialize(file_path)
+    @file_path = file_path
+    @mapping = {
+      'L' => :-,
+      'R' => :+
+    }
+  end
+
+  def decode(debug: false)
+    code = 0
+    current_num = 50
+    puts "The dial starts by pointing at #{current_num}" if debug
+    File.readlines(@file_path, chomp: true).map do |line|
+      next if line.nil? || line.empty?
+
+      direction, *number_arr = line.split('')
+      number = Integer(number_arr.join)
+      current_num = current_num.send(@mapping[direction], number) % 100
+      code += 1 if current_num == 0
+      puts "The dial is rotaded #{line} to point at #{current_num}" if debug
+    end
+
+    code
+  end
+end
+
+rd = RotationDecoder.new('input.txt')
+puts "The code is: #{rd.decode}"

mark/day1/part2.rb

@@ -0,0 +1,53 @@
+require 'debug'
+
+class RotationDecoder
+  def initialize(file_path)
+    @file_path = file_path
+    @mapping = {
+      'L' => :-,
+      'R' => :+
+    }
+  end
+
+  def decode(debug: false)
+    code = 0
+    current_num = 50
+    puts "The dial starts by pointing at #{current_num}" if debug
+    File.readlines(@file_path, chomp: true).map do |line|
+      next if line.nil? || line.empty?
+      direction, *number_arr = line.split('')
+      number = Integer(number_arr.join)
+
+      full_rotations = number / 100
+      rest = number - full_rotations * 100
+
+      raw_num = current_num.send(@mapping[direction], rest)
+
+      # include 100 since that does not pass *through* zero but becomes exactly zero.
+      passes_zero = 0
+
+      if current_num != 0
+        passes_zero = (0 <= raw_num && raw_num <= 100)  ? 0 : 1
+      end
+
+      current_num = raw_num % 100
+      print "The dial is rotaded #{line} to point at #{current_num}" if debug
+      print "; during this rotation, it points at 0 #{full_rotations + passes_zero} times" if debug && full_rotations + passes_zero > 0
+      print "\n" if debug
+
+      code += full_rotations + passes_zero
+      code += 1 if current_num == 0
+    end
+
+    code
+  end
+end
+
+if ARGV[0].nil? || ARGV[0].empty?
+  puts "Usage: ruby part2.rb <file_name> [debug]"
+  exit 1
+end
+
+debug = (ARGV[1] == "debug")
+rd = RotationDecoder.new(ARGV[0])
+puts "The code is: #{rd.decode(debug:)}"

mark/day2/example.txt

@@ -0,0 +1 @@
+11-22,95-115,998-1012,1188511880-1188511890,222220-222224,1698522-1698528,446443-446449,38593856-38593862,565653-565659,824824821-824824827,2121212118-2121212124

mark/day2/input.txt

@@ -0,0 +1 @@
+1090286-1131879,3259566-3404881,138124-175118,266204727-266361099,16765-24272,7657360692-7657593676,88857504-88926597,6869078-6903096,48444999-48532270,61427792-61580535,71-103,8077-10421,1920-2560,2-17,951-1259,34-50,28994-36978,1309-1822,9393918461-9393960770,89479-120899,834641-988077,5389718924-5389797353,34010076-34214499,5063-7100,607034-753348,19098586-19261191,125085556-125188689,39839-51927,3246-5037,174-260,439715-473176,187287-262190,348-535,58956-78301,4388160-4505757,512092-584994,13388753-13534387

mark/day2/part1.rb

@@ -0,0 +1,57 @@
+require 'debug'
+
+class ValidIdFilter
+  def initialize(file_path)
+    @file_path = file_path
+  end
+
+  def sum_invalid_ids(debug: false)
+    ranges = parse_input(File.read(@file_path))
+    invalid_ids = ranges.flat_map {|range| get_invalid_ids_from_range(range)}
+    invalid_ids.sum
+  end
+
+  private
+
+  # @param [Range] e.g., 11-22
+  # @return [<Integer>] array of invalid ids in range
+  def get_invalid_ids_from_range(range)
+    range.select {|element| invalid_id?(element)}
+  end
+
+  def invalid_id?(integer)
+    # ID is invalid if it is made only of some sequence of digits repeated twice
+    string = integer.to_s
+    num_digits = string.length
+
+    # some sequence repeated twice => number of digits must be even
+    return false if num_digits % 2 != 0
+
+    half_length = num_digits / 2
+
+    string[0...half_length] == string[half_length..-1]
+  end
+
+  # @param [String] full input e.g., "11-22,33-604,..."
+  # @return [<Range>] e.g., [11..22, 33..604, ...]
+  def parse_input(input)
+    input.split(',').map {|range| to_range(range)}
+  end
+
+  # @param [String] e.g., "11-22"
+  # @return [Range] e.g., 11..22 (inclusive)
+  def to_range(string)
+    boundaries = string.split('-').map(&:to_i)
+    raise "Invalid boundaries for #{string}, got #{boundaries.inspect}" if boundaries.length != 2
+    Range.new(boundaries[0], boundaries[1])
+  end
+end
+
+if ARGV[0].nil? || ARGV[0].empty?
+  puts "Usage: ruby part1.rb <file_name> [debug]"
+  exit 1
+end
+
+debug = (ARGV[1] == "debug")
+filter = ValidIdFilter.new(ARGV[0])
+puts "The answer is: #{filter.sum_invalid_ids(debug:)}"

mark/day2/part2.rb

@@ -0,0 +1,74 @@
+require 'debug'
+require 'prime'
+
+class ValidIdFilter
+  def initialize(file_path, debug: false)
+    @file_path = file_path
+    @debug = debug
+  end
+
+  def sum_invalid_ids
+    ranges = parse_input(File.read(@file_path))
+    invalid_ids = ranges.flat_map {|range| get_invalid_ids_from_range(range)}
+    puts invalid_ids.inspect if @debug
+    invalid_ids.sum
+  end
+
+  private
+
+  # @param [Range] e.g., 11-22
+  # @return [<Integer>] array of invalid ids in range
+  def get_invalid_ids_from_range(range)
+    range.select do |element|
+      invalid_id?(element)
+    end
+  end
+
+  def invalid_id?(integer)
+    # ID is invalid if it is made only of some sequence of digits repeated AT LEAST twice
+    string = integer.to_s
+    num_digits = string.length
+
+    puts "is #{string} an invalid ID?" if @debug
+
+    (1...num_digits).each do |n|
+      next if num_digits % n != 0
+
+      slices = string.chars.each_slice(n).map(&:join)
+      puts "...trying divisior #{n}: #{slices} ..." if @debug
+      return true if slices.uniq.length == 1 && slices.length > 1
+    end
+
+    false
+  end
+
+  # @param [String] full input e.g., "11-22,33-604,..."
+  # @return [<Range>] e.g., [11..22, 33..604, ...]
+  def parse_input(input)
+    input.split(',').map {|range| to_range(range)}
+  end
+
+  # @param [String] e.g., "11-22"
+  # @return [Range] e.g., 11..22 (inclusive)
+  def to_range(string)
+    boundaries = string.split('-').map(&:to_i)
+    raise "Invalid boundaries for #{string}, got #{boundaries.inspect}" if boundaries.length != 2
+    Range.new(boundaries[0], boundaries[1])
+  end
+end
+
+if ARGV[0].nil? || ARGV[0].empty?
+  puts "Usage: ruby part2.rb <file_name> [debug]"
+  exit 1
+end
+
+debug = (ARGV[1] == "debug")
+filter = ValidIdFilter.new(ARGV[0], debug:)
+puts "The answer is: #{filter.sum_invalid_ids}"
+
+# The answer is: 41662374059
+
+# real	0m24,122s
+# user	0m24,049s
+# sys	0m0,070s
+

mark/day3/example.txt

@@ -0,0 +1,4 @@
+987654321111111
+811111111111119
+234234234234278
+818181911112111

mark/day3/input.txt

@@ -0,0 +1,200 @@
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mark/day3/part1.rb

@@ -0,0 +1,49 @@
+require 'debug'
+
+module FileHandler
+  def self.read_lines(file_path)
+    File.readlines(file_path, chomp: true).map do |line|
+      yield(line)
+    end
+  end
+
+  def self.read_file(file_path)
+    File.read(file_path)
+  end
+end
+
+class JoltageCalculator
+  def initialize(file_path, debug: false)
+    @file_path = file_path
+    @debug = debug
+  end
+
+  def calculate_total_joltage
+    total = 0
+    FileHandler.read_lines(@file_path) do |line|
+      int_array = line.split('').map(&:to_i)
+      length = int_array.length
+      first_digit = int_array.slice(0, length - 1).max
+      first_pos = int_array.find_index(first_digit)
+      second_digit = int_array.slice(first_pos + 1, length).max
+      total += "#{first_digit}#{second_digit}".to_i
+    end
+    total
+  end
+end
+
+if ARGV[0].nil? || ARGV[0].empty?
+  puts "Usage: ruby part1.rb <file_name> [debug]"
+  exit 1
+end
+
+debug = (ARGV[1] == "debug")
+calculator = JoltageCalculator.new(ARGV[0], debug:)
+puts "The answer is: #{calculator.calculate_total_joltage}"
+
+# The answer is: 17166
+
+# real	0m0,256s
+# user	0m0,207s
+# sys	0m0,049s
+

mark/day3/part1_prep_for_2.rb

@@ -0,0 +1,67 @@
+require 'debug'
+
+module FileHandler
+  def self.read_lines(file_path)
+    File.readlines(file_path, chomp: true).map do |line|
+      yield(line)
+    end
+  end
+
+  def self.read_file(file_path)
+    File.read(file_path)
+  end
+end
+
+class JoltageCalculator
+  def initialize(file_path, debug: false)
+    @file_path = file_path
+    @debug = debug
+  end
+
+  def calculate_total_joltage
+    total = 0
+    FileHandler.read_lines(@file_path) do |line|
+      int_array = line.split('').map(&:to_i)
+      total += calculate_joltage(int_array)
+    end
+    total
+  end
+
+  # @param [<integer>] bank
+  def calculate_joltage(bank)
+    joltage = ''
+
+    first_digit, first_pos = max_and_index_from_slice(bank, 1)
+
+    joltage += first_digit.to_s
+
+
+    sub_bank = bank.slice(first_pos + 1, bank.length)
+    second_digit, _ = max_and_index_from_slice(sub_bank, 0)
+
+    joltage += second_digit.to_s
+
+    joltage.to_i
+  end
+
+  private
+
+  # Get max and index from the first part of the array. Ignore the last `offset`
+  # number of digits.
+  # @param [<integer>] array
+  # @param [integer] offset
+  def max_and_index_from_slice(array, offset)
+    maximum = array.slice(0, array.length - offset).max
+    index = array.find_index(maximum)
+    [maximum, index]
+  end
+end
+
+if ARGV[0].nil? || ARGV[0].empty?
+  puts "Usage: ruby part2.rb <file_name> [debug]"
+  exit 1
+end
+
+debug = (ARGV[1] == "debug")
+calculator = JoltageCalculator.new(ARGV[0], debug:)
+puts "The answer is: #{calculator.calculate_total_joltage}"

mark/day3/part2.rb

@@ -0,0 +1,91 @@
+require 'debug'
+
+module FileHandler
+  def self.read_lines(file_path)
+    File.readlines(file_path, chomp: true).map do |line|
+      yield(line)
+    end
+  end
+
+  def self.read_file(file_path)
+    File.read(file_path)
+  end
+end
+
+class JoltageCalculator
+  def initialize(file_path, debug: false)
+    @file_path = file_path
+    @debug = debug
+  end
+
+  def calculate_total_joltage
+    total = 0
+    FileHandler.read_lines(@file_path) do |line|
+      int_array = line.split('').map(&:to_i)
+      total += calculate_joltage(int_array)
+    end
+    total
+  end
+
+  # @param [<integer>] bank
+  def _calculate_joltage(bank)
+    joltage = ''
+
+    first_digit, first_pos = max_and_index_from_slice(bank, 1)
+
+    joltage += first_digit.to_s
+
+
+    sub_bank = bank.slice(first_pos + 1, bank.length)
+    second_digit, _ = max_and_index_from_slice(sub_bank, 0)
+
+    joltage += second_digit.to_s
+
+    joltage.to_i
+  end
+
+  # @param [<integer>] bank
+  def calculate_joltage(bank, total_digits: 12)
+    joltage = ''
+
+    current_offset = total_digits - 1
+
+    while current_offset >= 0
+      maximum, i = max_and_index_from_slice(bank, current_offset)
+
+      joltage += maximum.to_s
+
+      bank = bank.slice(i + 1, bank.length)
+      current_offset -= 1
+    end
+
+    joltage.to_i
+  end
+
+  private
+
+  # Get max and index from the first part of the array. Ignore the last `offset`
+  # number of digits.
+  # @param [<integer>] array
+  # @param [integer] offset
+  def max_and_index_from_slice(array, offset)
+    maximum = array.slice(0, array.length - offset).max
+    index = array.find_index(maximum)
+    [maximum, index]
+  end
+end
+
+if ARGV[0].nil? || ARGV[0].empty?
+  puts "Usage: ruby part2.rb <file_name> [debug]"
+  exit 1
+end
+
+debug = (ARGV[1] == "debug")
+calculator = JoltageCalculator.new(ARGV[0], debug:)
+puts "The answer is: #{calculator.calculate_total_joltage}"
+
+# The answer is: 169077317650774
+
+# real	0m0,260s
+# user	0m0,222s
+# sys	0m0,038s