Step by Step solution about How to resolve the algorithm Doubly-linked list/Element insertion step by step in the Ruby programming language

The provided Ruby code defines a method, insert_after, for a doubly linked list node (DListNode). This method is used to insert a new value into the list after a specified search value. A doubly linked list is a data structure that stores data in nodes connected by pointers in both directions, allowing for efficient insertion and deletion operations.

An overview of the insert_after method:

1. It takes two arguments: search_value, which specifies the value to search for in the list, and new_value, which is the value to be inserted after the search value.

2. The implementation first checks if the search_value is equal to the value stored in the current node. If they are equal, it means the search value has been found.

3. If the search value is found, it creates a new node (new_node) using the DListNode class and initializes it with the new_value, as well as setting its prev and succ (predecessor and successor) pointers to nil.

4. It then sets the succ pointer of the current node to point to the new node (new_node).

5. It updates the prev pointer of the new node to point to the current node (self).

6. It updates the succ pointer of the new node to point to the current node's successor (next_node).

7. Finally, it updates the prev pointer of the current node's successor to point to the new node (new_node).

8. If the search value is not found in the current node, it checks if its successor (succ) is nil. If the successor is nil, it means the end of the list has been reached, and it raises a StandardError with a message indicating that the search_value was not found in the list.

9. If the search value is not found in the current node and its successor is not nil, it recursively calls the insert_after method on its successor, passing in the search_value and new_value arguments. This allows the search to continue through the rest of the list.

In the example provided at the end of the code, a doubly linked list is initialized with the values [:a, :b] using head = DListNode.from_array([:a, :b]). Then, the insert_after method is called on the head node, passing in :a as the search_value and :c as the new_value. This results in the new value :c being inserted into the list after the value :a. The resulting linked list would be [:a, :c, :b].

class DListNode
  def insert_after(search_value, new_value)
    if search_value == value
      new_node = self.class.new(new_value, nil, nil)
      next_node = self.succ
      self.succ = new_node
      new_node.prev = self
      new_node.succ = next_node
      next_node.prev = new_node
    elsif self.succ.nil?
      raise StandardError, "value #{search_value} not found in list"
    else
      self.succ.insert_after(search_value, new_value)
    end
  end
end

head = DListNode.from_array([:a, :b])
head.insert_after(:a, :c)