Monday, March 8, 2021

(trees) vs (binary trees) vs (binary search trees) in computer science

 not completely the same




avl trees , red black trees - built-in balancing mechanisms

 

algorithms for shifting while inserting or deleting built in to keep binary tree  "logarithmic in height"  rather than  "linear in height"


inserting into a balanced binary tree is indeed big O of logn , but that depends on the prerequisite of you keeping the binary search tree balanced



source: cs50



sorting algorithms - bubble sort, insertion sort, selection sort, merge sort

  source: harvard cs50 

Data structures comparison - arrays, linked lists, hash tables, tries

 

Arrays:

- insertion is bad - lots of shifting to fit an element in the middle (except for inserting at the end of the array, anywhere other than the end of the array is not so great)

- deletion is bad - lots of shifting after removing an element (except for deleting from the end of the array, unless we don't care about leaving empty gaps, which we usually don't want)

- lookup is great - random access, constant time 

- relatively easy to sort

- relatively small size-wise

- stuck with a fixed size, no flexibility



Linked lists:

- insertion is easy - just tack onto the front

- deletion is easy - once you find the element

- lookup is bad - have to rely on linear search

- relatively difficult to sort - unless you are willing to compromise on super-fast insertion and instead sort as you construct

- relatively small size-wise



Hash tables:

- insertion is a two-step process - hash, and then add

- deletion is easy - once you find the element

- lookup is on average better than with linked lists because you have the benefit of a real-world constant factor

- not an ideal data structure if sorting is the goal - just use an array

- can run the gamut of size




 



source: harvard cs50 david malan



linked list - big O of n

 


source: harvard cs50, david malan

what is the running time of inserting into a binary search tree?

 big O of  logn


things related to binary search are often  big O of logn


if you have a well-balanced binary tree, if it has a total of n nodes, then  log-based-2-of-n will be the height of the tree


source: harvard, cs50, david malan