diff --git a/lib/linked_list.rb b/lib/linked_list.rb index 5e173ebc..91fa2dbd 100644 --- a/lib/linked_list.rb +++ b/lib/linked_list.rb @@ -18,24 +18,41 @@ 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 - # Time Complexity: ? - # Space Complexity: ? + # Time Complexity: O(1) + # Space Complexity: O(1) def add_first(value) - raise NotImplementedError + new_node = Node.new(value, @head) + @head = new_node end # method to find if the linked list contains a node with specified value # returns true if found, false otherwise - # Time Complexity: ? - # Space Complexity: ? + # Time Complexity: O(n) + # Space Complexity: O(1) def search(value) - raise NotImplementedError + current = @head + until current.nil? + return true if current.data == value + current = current.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 + return nil if @head.nil? + + current = @head + max = current.data + + until current.nil? + if current.data > max + max = current.data + end + current = current.next + end + return max end # method to return the min value in the linked list @@ -43,31 +60,55 @@ def find_max # Time Complexity: ? # Space Complexity: ? def find_min - raise NotImplementedError + return nil if @head.nil? + + current = @head + min = current.data + + until current.nil? + if current.data < min + min = current.data + end + current = current.next + end + return min end # Additional Exercises # returns the value in the first node # returns nil if the list is empty - # Time Complexity: ? - # Space Complexity: ? + # Time Complexity: O(1) + # Space Complexity: O(1) def get_first - raise NotImplementedError + return nil if @head.nil? + + return @head.data end # method that inserts a given value as a new last node in the linked list # Time Complexity: ? # Space Complexity: ? def add_last(value) - raise NotImplementedError + current = @head + + until current.nil? + current = current.next + end + current = Node.new(value) end # method that returns the length of the singly linked list - # Time Complexity: ? - # Space Complexity: ? + # Time Complexity: O(n) + # Space Complexity: O(1) 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 @@ -76,7 +117,19 @@ def length # Time Complexity: ? # Space Complexity: ? def get_at_index(index) - raise NotImplementedError + return nil if @head.nil? + + length = 0 + + current = @head + + until length == index || current.nil? + current = current.next + length += 1 + end + + return nil if length < index + return current.data end # method to print all the values in the linked list