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Ports - Kasey #34

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Ports - Kasey #34

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04e9ca9
some of the stuff
kaseea Aug 26, 2019
d24bb5d
Merge branch 'master' of https://github.com/Ada-C11/linked-list
kaseea Aug 26, 2019
f90b4b8
all passing
kaseea Sep 3, 2019
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332 changes: 217 additions & 115 deletions lib/linked_list.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -12,152 +12,254 @@ 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
# 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: O(1)
# Space Complexity n?
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Actually O(1) since you're only adding 1 node to the list.

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
# method to find if the linked list contains a node with specified value
# returns true if found, false otherwise
# Time Complexity: O(n)
# Space Complexity O(1)
def search(value)
node = @head
while node != nil
if node.data == value
return true
end
node = node.next
end
return false
end

# method to return the max value in the linked list
# returns the data value and not the node
# Time Complexity:
# Space Complexity
def find_max
raise NotImplementedError
# 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
if @head == nil
return nil
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
max = @head.data
current = @head
while current != nil
if current.data > max
max = current.data
end
current = current.next
end
return max
end


# method that returns the length of the singly linked list
# Time Complexity:
# Space Complexity
def length
raise NotImplementedError
# method to return the min value in the linked list
# returns the data value and not the node
# Time Complexity: O(n)
# Space Complexity O(1)
def find_min
if @head == nil
return nil
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
node = @head
min = node.data
while node != nil
if node.data < min
min = node.data
end
node = node.next
end
return min
end

# method to print all the values in the linked list
# Time Complexity:
# Space Complexity
def visit
raise NotImplementedError
# method that returns the length of the singly linked list
# Time Complexity: O(n)
# Space Complexity O(1)
def length
return 0 if !@head
length = 0
current = @head
while current != nil
length += 1
current = current.next
end
return length
end

# method to delete the first node found with specified value
# Time Complexity:
# Space Complexity
def delete(value)
raise NotImplementedError
# 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: O(n)
# Space Complexity O(1)
def get_at_index(index)
length = 0
current = @head
while current != nil
if length == index
return current.data
end
length += 1
current = current.next
end
return nil
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
# method to print all the values in the linked list
# Time Complexity: O(n)
# Space Complexity O(1)
def visit
current = @head
while current != nil
puts current.data
current = current.next
end
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
# method to delete the first node found with specified value
# Time Complexity: O(n)
# Space Complexity constant
def delete(value)
if @head == nil
return nil
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
if @head.data == value
@head = @head.next
else
current = @head
while current.next != nil
if current.next.data == value
current.next = current.next.next
break
end
current = current.next
end
end
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
# method to reverse the singly linked list
# note: the nodes should be moved and not just the values in the nodes
# Time Complexity: O(n)
# Space Complexity almost constant, needs three pointers allocated
def reverse
#going to need three pointers
prev = nil
current = @head
while current != nil
temp = current.next
current.next = prev
prev = current
current = temp
end
@head = prev
end

## Advanced Exercises
# returns the value at the middle element in the singly linked list
# Time Complexity:
# Space Complexity
Comment on lines +165 to +166
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Time & Space complexity?

def find_middle_value
length = self.length
return self.get_at_index(length / 2 - 1)
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
# find the nth node from the end and return its value
# assume indexing starts at 0 while counting to n
# Time Complexity: O(n) + N
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You can actually do this in O(n)

# Space Complexity O(1)
def find_nth_from_end(n)
length = self.length
if n > length
return nil
else
return self.get_at_index(length - n - 1)
end
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
# 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
# does this just mean an infinite loop?
raise NotImplementedError
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
# Additional Exercises
# returns the value in the first node
# returns nil if the list is empty
# Time Complexity: O(1)
# Space Complexity O(1)
def get_first
if @head == nil
return nil
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
if @head.data != nil
return @head.data
else
return nil
end
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
# method that inserts a given value as a new last node in the linked list
# Time Complexity: O(n)
# Space Complexity constant + 1?
def add_last(value)
puts value
last = Node.new(value)
if @head == nil
@head = last
else
current = @head
while current.next != nil
current = current.next
current = current.next
end
current.next = last
end
end

# method that returns the value of the last node in the linked list
# returns nil if the linked list is empty
# Time Complexity: O(n)
# Space Complexity constant
def get_last
return nil if @head == nil
val = @head.data
current = @head
while current != nil
val = current.data
current = current.next
end
return val
end

current.next = @head # make the last node link to first node
# 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

# 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
end