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Jou-Jou's Linked Lists#5

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Jou-Jou's Linked Lists#5
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@jjousun jjousun commented Aug 27, 2017

Linked Lists

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Comprehension Questions

What is the time and space complexity for each method you implemented? Provide justification.

Question Answer
What is the time complexity of the insert method? Provide justification. O(1). Since we're adding to the beginning, it takes constant time to find the beginning and to insert
What is the space complexity of the insert method? Provide justification. O(1). The new node created doesn't vary depending on input size (since it's always one at a time).
What is the time complexity of the search method? Provide justification. O(n). Must visit every node once.
What is the space complexity of the search method? Provide justification. O(1). A pointer (or reference) is created to move along the linked list, but this doesn't change.
What is the time complexity of the find_max method? Provide justification. O(n). Must visit every node once.
What is the space complexity of the find_max method? Provide justification. O(1). A pointer (or reference) is created to move along the linked list, but this doesn't change.
What is the time complexity of the find_min method? Provide justification. O(n). Must visit every node once.
What is the space complexity of the find_min method? Provide justification. O(1). A pointer (or reference) is created to move along the linked list, but this doesn't change.
What is the time complexity of the length method? Provide justification. O(n). Must visit every node once.
What is the space complexity of the length method? Provide justification. O(1). Additional storage doesn't depend on input size.
What is the time complexity of the find_nth_from_beginning method? Provide justification. O(n). Must visit every node (in worst case).
What is the space complexity of the find_nth_from_beginning method? Provide justification. O(1). Additional storage doesn't depend on input size.
What is the time complexity of the insert_ascending method? Provide justification. O(n). Must visit every node to find the place to insert. O(1) to insert, so O(n) overall.
What is the space complexity of the insert_ascending method? Provide justification. O(1). Doesn't depend on input size.
What is the time complexity of the visit method? Provide justification. O(n). Must visit every node.
What is the space complexity of the visit method? Provide justification. O(1). Doesn't depend on input size.
What is the time complexity of the delete method? Provide justification. O(n). O(n) to find the node to delete (visiting, in worst case, every node), and the O(1) to delete. So O(n) overall.
What is the space complexity of the delete method? Provide justification. O(1). Doesn't change if size of linked list changes.
What is the time complexity of the reverse method? Provide justification. O(n). Visit every node once.
What is the space complexity of the reverse method? Provide justification. O(1). Additional storage doesn't change if size of linked list changes.
What is the time complexity of the find_middle_value method? Provide justification. O(n). Must visit every node once.
What is the space complexity of the find_middle_value method? Provide justification. O(1). Additional storage doesn't depend on size of linked list.
What is the time complexity of the find_nth_from_end method? Provide justification. O(n). Must go through the entire linked list.
What is the space complexity of the find_nth_from_end method? Provide justification. O(1). Additional storage remains constant even if linked list size changes.
What is the time complexity of the has_cycle method? Provide justification. O(n). Even if there is a cycle, must go through the entire linked list (although technically it might be a little longer than O(n) in order to catch the cycle, I think it still comes out to linear time). i.e. mathematically it might be like O(n + n/2 + n/4 + n/8....)
What is the space complexity of the has_cycle method? Provide justification. O(1). Additional storage is constant despite input size.

shrutivanw
shrutivanw reviewed Oct 16, 2017
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linked_list.rb
def find_max
puts "Not implemented"
current = @head
max = current
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@shrutivanw shrutivanw Oct 16, 2017

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What is head is nil? You won't be able to return max.data in that case. Always check for nil before dereferencing.

shrutivanw
shrutivanw reviewed Oct 16, 2017
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linked_list.rb
def find_min
puts "Not implemented"
current = @head
min = current.data # not sure why in the previous menthod couldn't use .data here
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@shrutivanw shrutivanw Oct 16, 2017

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Same comment as above. Check if current is nil before accessing current.data.

shrutivanw
shrutivanw reviewed Oct 16, 2017
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linked_list.rb
i = 0

until i == n
current = current.next
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Check for nil before moving to next. Check for the case where the linked list has less than n nodes.

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@jjousun @shrutivanw @jjjousun