diff --git a/.idea/.gitignore b/.idea/.gitignore new file mode 100644 index 00000000..73f69e09 --- /dev/null +++ b/.idea/.gitignore @@ -0,0 +1,8 @@ +# Default ignored files +/shelf/ +/workspace.xml +# Datasource local storage ignored files +/dataSources/ +/dataSources.local.xml +# Editor-based HTTP Client requests +/httpRequests/ diff --git a/.idea/linked-list.iml b/.idea/linked-list.iml new file mode 100644 index 00000000..5b367f53 --- /dev/null +++ b/.idea/linked-list.iml @@ -0,0 +1,32 @@ + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + \ No newline at end of file diff --git a/.idea/misc.xml b/.idea/misc.xml new file mode 100644 index 00000000..39160804 --- /dev/null +++ b/.idea/misc.xml @@ -0,0 +1,4 @@ + + + + \ No newline at end of file diff --git a/.idea/modules.xml b/.idea/modules.xml new file mode 100644 index 00000000..a096c061 --- /dev/null +++ b/.idea/modules.xml @@ -0,0 +1,8 @@ + + + + + + + + \ No newline at end of file diff --git a/.idea/vcs.xml b/.idea/vcs.xml new file mode 100644 index 00000000..94a25f7f --- /dev/null +++ b/.idea/vcs.xml @@ -0,0 +1,6 @@ + + + + + + \ No newline at end of file diff --git a/Gemfile b/Gemfile index 04a9dcdd..0a8603d1 100644 --- a/Gemfile +++ b/Gemfile @@ -7,4 +7,7 @@ gem 'minitest-spec' gem 'minitest-reporters' gem "pry" gem 'minitest-skip' +gem 'minitest', group: :test +gem 'minitest-reporters', group: :test + diff --git a/lib/linked_list.rb b/lib/linked_list.rb index 5e173ebc..83d66ff7 100644 --- a/lib/linked_list.rb +++ b/lib/linked_list.rb @@ -12,148 +12,204 @@ def initialize(value, next_node = nil) # Defines the singly linked list class LinkedList - def initialize - @head = nil # keep the head private. Not accessible outside this class - end - + def initialize + @head = nil # keep the head private. Not accessible outside this class + end # 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: ? - def add_first(value) - raise NotImplementedError - end - + # Time Complexity: O(1) + # Space Complexity:? O(1) + def add_first(value) + new_node = Node.new(value) + new_node.next = @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: ? - def search(value) - raise NotImplementedError + # Time Complexity: O(n) + # Space Complexity: O(n) + def search(value) + current_node = @head + + while current_node + if current_node.data == value + return true + end + current_node = current_node.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 + def find_max + current_node = @head + max = current_node.data + current_node = current_node.next + + while current_node != nil + if current_node.data > max + max = current_node.data + end + current_node = current_node.next end - + return max + end # method to return the min value in the linked list # returns the data value and not the node - # Time Complexity: ? - # Space Complexity: ? - def find_min - raise NotImplementedError + # Time Complexity: O(n) + # Space Complexity: O(1) + def find_min + current_node = @head + min = current_node.data + current_node = current_node.next + + while current_node != nil + if current_node.data < min + min = current_node.data + end + current_node = current_node.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: ? - def get_first - raise NotImplementedError - end - + # Time Complexity: O(1) + # Space Complexity: O(1) + def get_first + 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 - end - + # Time Complexity: O(n) + # Space Complexity: O(1) + def add_last(value) + return @head = Node.new(value) if @head.nil? + current_node= @head + while current_node.next != nil + current_node= current_node.next + end + current_node.next = Node.new(value) + end # method that returns the length of the singly linked list - # Time Complexity: ? - # Space Complexity: ? - def length - raise NotImplementedError + # Time Complexity: O(n) + # Space Complexity: O(1) + def length + current_node = @head + count = 0 + + while current_node != nil + count += 1 + current_node = current_node.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 - # Time Complexity: ? - # Space Complexity: ? - def get_at_index(index) - raise NotImplementedError - end - + # Time Complexity: O(n) + # Space Complexity: O(1) + def get_at_index(index) + current_node = @head + i = 0 + + while current_node != nil + if i == index + return current_node.data + end + current_node = current_node.next + i += 1 + end + return nil + end # method to print all the values in the linked list - # Time Complexity: ? - # Space Complexity: ? - def visit - raise NotImplementedError + # Time Complexity: O(n) + # Space Complexity: O(1) + def visit + return nil if @head.nil? + current_node = @head + while current_node != nil + print current_node.data + current_node = current_node.next end - + end # method to delete the first node found with specified value - # Time Complexity: ? - # Space Complexity: ? - def delete(value) - raise NotImplementedError - end - + # Time Complexity: + # Space Complexity: + def delete(value) + # ?? + end # method to reverse the singly linked list # note: the nodes should be moved and not just the values in the nodes - # Time Complexity: ? - # Space Complexity: ? - def reverse - raise NotImplementedError - end - + # Time Complexity: O(n) + # Space Complexity: O(1) + def reverse + current_node = @head + previous_node = nil + + while current_node != nil + next_node = current_node.next + current_node.next = previous_node + previous_node = current_node + current_node = next_node + end + @head = previous_node + end # method that returns the value of the last node in the linked list # returns nil if the linked list is empty - # Time Complexity: ? - # Space Complexity: ? - def get_last - raise NotImplementedError + # Time Complexity: O(n) + # Space Complexity: O(1) + def get_last + if @head == nil + return + end + + current_node = @head + while current_node.next != nil + current_node = current_node.next end - + current_node.next = @head + end ## Advanced Exercises # returns the value at the middle element in the singly linked list # Time Complexity: ? # Space Complexity: ? - def find_middle_value - raise NotImplementedError - end - + def find_middle_value + raise NotImplementedError + end # find the nth node from the end and return its value # assume indexing starts at 0 while counting to n # Time Complexity: ? # Space Complexity: ? - def find_nth_from_end(n) - raise NotImplementedError - end - + def find_nth_from_end(n) + raise NotImplementedError + end # checks if the linked list has a cycle. A cycle exists if any node in the # linked list links to a node already visited. # returns true if a cycle is found, false otherwise. # Time Complexity: ? # Space Complexity: ? - def has_cycle - raise NotImplementedError - end - + def has_cycle + raise NotImplementedError + end # method to insert a new node with specific data value, assuming the linked # list is sorted in ascending order # Time Complexity: ? # Space Complexity: ? - def insert_ascending(value) - raise NotImplementedError - end - + def insert_ascending(value) + raise NotImplementedError + end # Helper method for tests # Creates a cycle in the linked list for testing purposes # Assumes the linked list has at least one node - def create_cycle - return if @head == nil # don't do anything if the linked list is empty - - # navigate to last node - current = @head - while current.next != nil - current = current.next - end - - current.next = @head # make the last node link to first node - end + def create_cycle + return if @head == nil # don't do anything if the linked list is empty + # navigate to last node + current = @head + while current.next != nil + current = current.next + end + current.next = @head # make the last node link to first node + end end diff --git a/test/linked_list_test.rb b/test/linked_list_test.rb index 77423e34..b6246f93 100644 --- a/test/linked_list_test.rb +++ b/test/linked_list_test.rb @@ -1,3 +1,5 @@ + + require_relative 'test_helper' diff --git a/test/test_helper.rb b/test/test_helper.rb index 100cecef..2ca42057 100644 --- a/test/test_helper.rb +++ b/test/test_helper.rb @@ -2,9 +2,8 @@ require 'minitest/autorun' require "minitest/reporters" require "minitest/skip_dsl" +require_relative '../lib/linked_list' Minitest::Reporters.use! Minitest::Reporters::SpecReporter.new - -require_relative '../lib/linked_list' - +Minitest::Reporters.use! \ No newline at end of file