Add the EN version of Ruby code.

Author: krahets

en/codes/ruby/chapter_array_and_linkedlist/array.rb

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+=begin
+File: array.rb
+Created Time: 2024-03-18
+Author: Xuan Khoa Tu Nguyen (ngxktuzkai2000@gmail.com)
+=end
+
+# ### Random access element ###
+def random_access(nums)
+  # Randomly select a number in the interval [0, nums.length)
+  random_index = Random.rand(0...nums.length)
+
+  # Retrieve and return the random element
+  nums[random_index]
+end
+
+
+# ### Extend array length ###
+# Note: Ruby's Array is dynamic array, can be directly expanded
+# For learning purposes, this function treats Array as fixed-length array
+def extend(nums, enlarge)
+  # Initialize an array with extended length
+  res = Array.new(nums.length + enlarge, 0)
+
+  # Copy all elements from the original array to the new array
+  for i in 0...nums.length
+    res[i] = nums[i]
+  end
+
+  # Return the extended new array
+  res
+end
+
+# ### Insert element num at index in array ###
+def insert(nums, num, index)
+  # Move all elements at and after index index backward by one position
+  for i in (nums.length - 1).downto(index + 1)
+    nums[i] = nums[i - 1]
+  end
+
+  # Assign num to the element at index index
+  nums[index] = num
+end
+
+
+# ### Delete element at index ###
+def remove(nums, index)
+  # Move all elements after index index forward by one position
+  for i in index...(nums.length - 1)
+    nums[i] = nums[i + 1]
+  end
+end
+
+# ### Traverse array ###
+def traverse(nums)
+  count = 0
+
+  # Traverse array by index
+  for i in 0...nums.length
+    count += nums[i]
+  end
+
+  # Direct traversal of array elements
+  for num in nums
+    count += num
+  end
+end
+
+# ### Find specified element in array ###
+def find(nums, target)
+  for i in 0...nums.length
+    return i if nums[i] == target
+  end
+
+  -1
+end
+
+
+### Driver Code ###
+if __FILE__ == $0
+  # Initialize array
+  arr = Array.new(5, 0)
+  puts "Array arr = #{arr}"
+  nums = [1, 3, 2, 5, 4]
+  puts "Array nums = #{nums}"
+
+  # Insert element
+  random_num = random_access(nums)
+  puts "Get random element #{random_num} from nums"
+
+  # Traverse array
+  nums = extend(nums, 3)
+  puts "Extend array length to 8, get nums = #{nums}"
+
+  # Insert element
+  insert(nums, 6, 3)
+  puts "Insert number 6 at index 3, get nums = #{nums}"
+
+  # Remove element
+  remove(nums, 2)
+  puts "Delete element at index 2, get nums = #{nums}"
+
+  # Traverse array
+  traverse(nums)
+
+  # Find element
+  index = find(nums, 3)
+  puts "Find element 3 in nums, index = #{index}"
+end

en/codes/ruby/chapter_array_and_linkedlist/linked_list.rb

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+=begin
+File: linked_list.rb
+Created Time: 2024-03-18
+Author: Xuan Khoa Tu Nguyen (ngxktuzkai2000@gmail.com)
+=end
+
+require_relative '../utils/list_node'
+require_relative '../utils/print_util'
+
+# ### Insert node _p after node n0 in linked list ###
+# Ruby's `p` is a built-in function, `P` is a constant, so use `_p` instead
+def insert(n0, _p)
+  n1 = n0.next
+  _p.next = n1
+  n0.next = _p
+end
+
+# ### Delete first node after node n0 in linked list ###
+def remove(n0)
+  return if n0.next.nil?
+
+  # n0 -> remove_node -> n1
+  remove_node = n0.next
+  n1 = remove_node.next
+  n0.next = n1
+end
+
+# ### Access node at index in linked list ###
+def access(head, index)
+  for i in 0...index
+    return nil if head.nil?
+    head = head.next
+  end
+
+  head
+end
+
+# ### Find first node with value target in linked list ###
+def find(head, target)
+  index = 0
+  while head
+    return index if head.val == target
+    head = head.next
+    index += 1
+  end
+
+  -1
+end
+
+### Driver Code ###
+if __FILE__ == $0
+  # Initialize linked list
+  # Initialize each node
+  n0 = ListNode.new(1)
+  n1 = ListNode.new(3)
+  n2 = ListNode.new(2)
+  n3 = ListNode.new(5)
+  n4 = ListNode.new(4)
+  # Build references between nodes
+  n0.next = n1
+  n1.next = n2
+  n2.next = n3
+  n3.next = n4
+  puts "Initialized linked list is"
+  print_linked_list(n0)
+
+  # Insert node
+  insert(n0, ListNode.new(0))
+  print_linked_list n0
+
+  # Remove node
+  remove(n0)
+  puts "Linked list after removing node is"
+  print_linked_list(n0)
+
+  # Access node
+  node = access(n0, 3)
+  puts "Value of node at index 3 in linked list = #{node.val}"
+
+  # Search node
+  index = find(n0, 2)
+  puts "Index of node with value 2 in linked list = #{index}"
+end

en/codes/ruby/chapter_array_and_linkedlist/list.rb

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+=begin
+File: list.rb
+Created Time: 2024-03-18
+Author: Xuan Khoa Tu Nguyen (ngxktuzkai2000@gmail.com)
+=end
+
+### Driver Code ###
+if __FILE__ == $0
+  # Initialize list
+  nums = [1, 3, 2, 5, 4]
+  puts "List nums = #{nums}"
+
+  # Update element
+  num = nums[1]
+  puts "Access element at index 1, get num = #{num}"
+
+  # Add elements at the end
+  nums[1] = 0
+  puts "Update element at index 1 to 0, get nums = #{nums}"
+
+  # Remove element
+  nums.clear
+  puts "After clearing list, nums = #{nums}"
+
+  # Direct traversal of list elements
+  nums << 1
+  nums << 3
+  nums << 2
+  nums << 5
+  nums << 4
+  puts "After adding elements, nums = #{nums}"
+
+  # Sort list
+  nums.insert(3, 6)
+  puts "Insert element 6 at index 3, get nums = #{nums}"
+
+  # Remove element
+  nums.delete_at(3)
+  puts "Delete element at index 3, get nums = #{nums}"
+
+  # Traverse list by index
+  count = 0
+  for i in 0...nums.length
+    count += nums[i]
+  end
+
+  # Directly traverse list elements
+  count = 0
+  nums.each do |x|
+    count += x
+  end
+
+  # Concatenate two lists
+  nums1 = [6, 8, 7, 10, 9]
+  nums += nums1
+  puts "After concatenating list nums1 to nums, get nums = #{nums}"
+
+  nums = nums.sort { |a, b| a <=> b }
+  puts "After sorting list, nums = #{nums}"
+end

en/codes/ruby/chapter_array_and_linkedlist/my_list.rb

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+=begin
+File: my_list.rb
+Created Time: 2024-03-18
+Author: Xuan Khoa Tu Nguyen (ngxktuzkai2000@gmail.com)
+=end
+
+# ### List class ###
+class MyList
+  attr_reader :size       # Get list length (current number of elements)
+  attr_reader :capacity   # Get list capacity
+
+  # ### Constructor ###
+  def initialize
+    @capacity = 10
+    @size = 0
+    @extend_ratio = 2
+    @arr = Array.new(capacity)
+  end
+
+  # ### Access element ###
+  def get(index)
+    # If the index is out of bounds, throw an exception, as below
+    raise IndexError, "Index out of bounds" if index < 0 || index >= size
+    @arr[index]
+  end
+
+  # ### Access element ###
+  def set(index, num)
+    raise IndexError, "Index out of bounds" if index < 0 || index >= size
+    @arr[index] = num
+  end
+
+  # ### Add element at end ###
+  def add(num)
+    # When the number of elements exceeds capacity, trigger the extension mechanism
+    extend_capacity if size == capacity
+    @arr[size] = num
+
+    # Update the number of elements
+    @size += 1
+  end
+
+  # ### Insert element in middle ###
+  def insert(index, num)
+    raise IndexError, "Index out of bounds" if index < 0 || index >= size
+
+    # When the number of elements exceeds capacity, trigger the extension mechanism
+    extend_capacity if size == capacity
+
+    # Move all elements after index index forward by one position
+    for j in (size - 1).downto(index)
+      @arr[j + 1] = @arr[j]
+    end
+    @arr[index] = num
+
+    # Update the number of elements
+    @size += 1
+  end
+
+  # ### Delete element ###
+  def remove(index)
+    raise IndexError, "Index out of bounds" if index < 0 || index >= size
+    num = @arr[index]
+
+    # Move all elements after index forward by one position
+    for j in index...size
+      @arr[j] = @arr[j + 1]
+    end
+
+    # Update the number of elements
+    @size -= 1
+
+    # Return the removed element
+    num
+  end
+
+  # ### Expand list capacity ###
+  def extend_capacity
+    # Create new array with length extend_ratio times original, copy original array to new array
+    arr = @arr.dup + Array.new(capacity * (@extend_ratio - 1))
+    # Add elements at the end
+    @capacity = arr.length
+  end
+
+  # ### Convert list to array ###
+  def to_array
+    sz = size
+    # Elements enqueue
+    arr = Array.new(sz)
+    for i in 0...sz
+      arr[i] = get(i)
+    end
+    arr
+  end
+end
+
+### Driver Code ###
+if __FILE__ == $0
+  # Initialize list
+  nums = MyList.new
+
+  # Direct traversal of list elements
+  nums.add(1)
+  nums.add(3)
+  nums.add(2)
+  nums.add(5)
+  nums.add(4)
+  puts "List nums = #{nums.to_array}, capacity = #{nums.capacity}, length = #{nums.size}"
+
+  # Sort list
+  nums.insert(3, 6)
+  puts "Insert number 6 at index 3, get nums = #{nums.to_array}"
+
+  # Remove element
+  nums.remove(3)
+  puts "Delete element at index 3, get nums = #{nums.to_array}"
+
+  # Update element
+  num = nums.get(1)
+  puts "Access element at index 1, get num = #{num}"
+
+  # Add elements at the end
+  nums.set(1, 0)
+  puts "Update element at index 1 to 0, get nums = #{nums.to_array}"
+
+  # Test capacity expansion mechanism
+  for i in 0...10
+    # At i = 5, the list length will exceed the list capacity, triggering the expansion mechanism
+    nums.add(i)
+  end
+  puts "After expansion, list nums = #{nums.to_array}, capacity = #{nums.capacity}, length = #{nums.size}"
+end