diff --git a/lib/linked_list.rb b/lib/linked_list.rb index 8dee5e8d..09e3d8cc 100644 --- a/lib/linked_list.rb +++ b/lib/linked_list.rb @@ -19,48 +19,105 @@ def initialize # method to add a new node with the specific data value in the linked list # insert the new node at the beginning of the linked list def add_first(value) - raise NotImplementedError + current_node = Node.new(value, @head) + @head = current_node end # method to find if the linked list contains a node with specified value # returns true if found, false otherwise def search(value) - raise NotImplementedError - end + temp = @head + until temp.nil? + if temp.data == value + return true + end + temp = temp.next + end + return false + end # method to return the max value in the linked list # returns the data value and not the node def find_max - raise NotImplementedError + max = nil + current = @head + until current.nil? + if max.nil? || current.data > max + max = current.data + end + current = current.next + end + return max end # method to return the min value in the linked list # returns the data value and not the node def find_min - raise NotImplementedError + min = nil + current = @head + until current.nil? + if min.nil? || current.data < min + min = current.data + end + current = current.next + end + return min end # method that returns the length of the singly linked list def length - raise NotImplementedError + count = 0 + current = @head + until current.nil? + count += 1 + current = current.next + end + return count end # method that returns the value at a given index in the linked list # index count starts at 0 # returns nil if there are fewer nodes in the linked list than the index value def get_at_index(index) - raise NotImplementedError + count = 0 + current = @head + + until current.nil? + count += 1 + if index == count + return current.data + end + + current = current.next + end + return nil end + # end # method to print all the values in the linked list def visit - raise NotImplementedError + print_all = nil + current = @head + until current.nil? + print current.data + current = current.next + end end # method to delete the first node found with specified value def delete(value) - raise NotImplementedError + if @head.nil? + return nil + end + + previous = @head + current = @head + until current.nil? || current.data == value + previous = current + current = current.next + end + previous.next = current.next end # method to reverse the singly linked list @@ -94,19 +151,44 @@ def has_cycle # returns the value in the first node # returns nil if the list is empty def get_first - raise NotImplementedError + if @head.nil? + return nil + else + return @head.data + end end # method that inserts a given value as a new last node in the linked list def add_last(value) - raise NotImplementedError + if @head.nil? + @head = Node.new(value, nil) + return + end + current = @head + until current.next.nil? + current = current.next + end + current.next = Node.new(value, nil) end + # method that returns the value of the last node in the linked list # returns nil if the linked list is empty - def get_last - raise NotImplementedError + def get_last(value) + previous = @head + current = @head + + until current.nil? + current = current.next + end + + previous = current + current = current.next + end + previous.next = current.next.data + return previous.next.data end +# got stuck here # method to insert a new node with specific data value, assuming the linked # list is sorted in ascending order