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/.rakeTasks b/.idea/.rakeTasks new file mode 100644 index 00000000..e409da2a --- /dev/null +++ b/.idea/.rakeTasks @@ -0,0 +1,7 @@ + + diff --git a/.idea/inspectionProfiles/Project_Default.xml b/.idea/inspectionProfiles/Project_Default.xml new file mode 100644 index 00000000..b0db9b0f --- /dev/null +++ b/.idea/inspectionProfiles/Project_Default.xml @@ -0,0 +1,6 @@ + + + + \ No newline at end of file diff --git a/.idea/linked-list.iml b/.idea/linked-list.iml new file mode 100644 index 00000000..28179284 --- /dev/null +++ b/.idea/linked-list.iml @@ -0,0 +1,27 @@ + + + + + + + + + + + + + + + + + + + + + + + + + + + \ No newline at end of file diff --git a/.idea/misc.xml b/.idea/misc.xml new file mode 100644 index 00000000..15ffe978 --- /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/lib/linked_list.rb b/lib/linked_list.rb index 0de1ee00..fd01dbbb 100644 --- a/lib/linked_list.rb +++ b/lib/linked_list.rb @@ -18,71 +18,163 @@ 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, nil) + new_node.next = @head + @head = new_node + return @head.data 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 + while 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 = @head.data + while 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 + while current != nil + if current.data < min_value + min_value = current.data + end + current = current.next + end + return min_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 + return 0 if @head.nil? + current = @head + length = 0 + while 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 + # traverse the list, + # index, number of times or + # until the end is reach + # Then return the current node's value + i = 0 + current = @head + while current != nil + if i == index + return current.data + else + i += 1 + current = current.next + end + end + + return nil + 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 + current = @head + while current !=nil + puts current.data + current = current.next + end end # method to delete the first node found with specified value - # Time Complexity: ? - # Space Complexity: ? + # Time Complexity: O(n) + # Space Complexity: O(1) def delete(value) - raise NotImplementedError + + if @head.nil? + return + end + + if @head.data == value + @head = @head.next + return + end + + current = @head + previous = nil + + while current != nil + if current.data == value + previous.next = current.next + end + previous = current + current = current.next + end 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: ? + # Time Complexity: O(n) + # Space Complexity: O(1) def reverse - raise NotImplementedError + if @head.nil? || @head.next.nil? + return @head + end + + current = @head + previous = nil + + while current != nil + temp = current.next + current.next = previous + previous = current + current = temp + end + @head = previous end @@ -118,7 +210,12 @@ def has_cycle # Time Complexity: ? # Space Complexity: ? def get_first - raise NotImplementedError + # return the value of the 1st node in the list + 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 @@ -133,6 +230,9 @@ def add_last(value) # Time Complexity: ? # Space Complexity: ? def get_last + # return nil if the list is empty + # otherwise traverse the list to the end + # Then return the last node's value raise NotImplementedError end