Module: Algorithmable::Cups::Primitives

Defined in:
lib/algorithmable/cups/primitives.rb

Instance Method Summary collapse

Instance Method Details

#chars_is_uniq?(string) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/algorithmable/cups/primitives.rb', line 33

def chars_is_uniq?(string)
  return unless string
  map = Array.new 127, false
  string.chars.each do |char|
    return false if map[char.ord]
    map[char.ord] = true
  end
end

#find_cycled_node(root) ⇒ Object 



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# File 'lib/algorithmable/cups/primitives.rb', line 73

def find_cycled_node(root)
  return unless root.next or root.next.next
  slow = root
  fast = root

  until fast.next.nil?
    slow = slow.next
    fast = fast.next.next
    break if slow == fast
  end

  # return, no cycle
  return if fast.next.nil?

  slow = root
  until slow == fast
    slow = slow.next
    fast = fast.next
  end

  # at this point return value is a node which is tail pointing to.
  fast
end

#remove_duplicated_chars(chars = []) ⇒ Object 



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# File 'lib/algorithmable/cups/primitives.rb', line 50

def remove_duplicated_chars(chars = [])
  return if chars.empty? || chars.size < 2
  array_tail = 1

  chars.size.times do |cur_char_index|
    next unless cur_char_index.nonzero?
    prev_char_index = 0

    while prev_char_index < array_tail
      break if chars[cur_char_index] == chars[prev_char_index]
      prev_char_index += 1
    end

    if prev_char_index == array_tail
      chars[array_tail] = chars[cur_char_index]
      array_tail += 1
    end
  end

  # trim all after new tail
  chars[0...array_tail]
end

#replace_space_chars(string, expression = '%20') ⇒ Object

this module contains a lot of C style code. It is done intentionally. All the methods avoiding using already existent algorithms in Ruby. Algorithms/solutions should be implemented in place



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# File 'lib/algorithmable/cups/primitives.rb', line 8

def replace_space_chars(string, expression = '%20')
  return unless string
  space_count = 0
  length = string.length
  replacement = expression.chars.reverse.freeze
  length.times { |i| space_count += 1 if string[i] == ' ' }
  new_length = length + space_count * 2
  chars = Array.new(new_length, ?\x00)

  (0..length.pred).to_a.reverse_each do |i|
    if string[i] == ' '
      replacement.each_with_index do |char, index|
        j = index + 1
        chars[new_length - j] = char
      end
      new_length = new_length - replacement.length
    else
      new_length -= 1
      chars[new_length] = string[i]
    end
  end

  chars.join
end

#reverse_string(string) ⇒ Object 



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# File 'lib/algorithmable/cups/primitives.rb', line 42

def reverse_string(string)
  return unless string
  chars = string.chars
  reversed = ''
  string.size.times { reversed << chars.pop }
  reversed
end