diff --git a/lib/linked_list.rb b/lib/linked_list.rb index 5e173ebc..dc422bfe 100644 --- a/lib/linked_list.rb +++ b/lib/linked_list.rb @@ -18,79 +18,150 @@ 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? + if current.data == value + return true + else + current = current.next + end + end + return false end # method to return the max value in the linked list # returns the data value and not the node + # Time Complexity: O(n) + # Space Complexity: O(1) def find_max - raise NotImplementedError + return nil if @head.nil? + current = @head + max_value = current.data + until current.nil? + if current.data > max_value + max_value = current.data + end + current = current.next + end + return max_value end # method to return the min value in the linked list # returns the data value and not the node - # Time Complexity: ? - # Space Complexity: ? + # Time Complexity: O(n) + # Space Complexity: O(1) def find_min - raise NotImplementedError + return nil if @head.nil? + current = @head + min_value = current.data + until current.nil? + if current.data < min_value + min_value = current.data + end + current = current.next + end + return min_value 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: ? + # Time Complexity: O(n) + # Space Complexity: O(1) 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 + length = 0 + current = @head + until current.nil? + length += 1 + current = current.next + end + return length 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 - # Time Complexity: ? - # Space Complexity: ? + # Time Complexity: O(n) + # Space Complexity: O(1) + def get_at_index(index) - raise NotImplementedError + return nil if @head.nil? + index_counter = 0 + current = @head + until index_counter == index || current.nil? + current = current.next + index_counter += 1 + end + if index_counter < index + return nil + else + return current.data + end end # method to print all the values in the linked list - # Time Complexity: ? - # Space Complexity: ? + # Time Complexity: O(n) + # Space Complexity: O(1) def visit - raise NotImplementedError + return nil if @head.nil? + current = @head + until current.nil? + print current.data + current = current.next + end end # method to delete the first node found with specified value # Time Complexity: ? # Space Complexity: ? + # 0 1 2 nil + # 2 + def delete(value) - raise NotImplementedError + return nil if @head.nil? + if @head.data == value + @head = @head.next + else + current = @head + until current.next.nil? + if current.next.data == value + current.next = current.next.next + end + current = current.next + end + end end # method to reverse the singly linked list @@ -106,7 +177,11 @@ def reverse # Time Complexity: ? # Space Complexity: ? def get_last - raise NotImplementedError + current = @head + until current.next.nil? + current = current.next + end + return current.data end ## Advanced Exercises