COP 3502 Spring 2018 Study Union Review

Transcription

1 Page 1 COP 3502 Spring 2018 Study Union Review Alec May Table of Contents: Tries 2 Heaps 3 Hash Tables 5 Base Conversion 6 Bitwise Operators 7 Backtracking 8 Sorts 9 Linked Lists 10 Tips and Resources 11

2 Page 2 For the following problems, assume we insert the following strings into a trie: Computer Compute CompSci CompEngi Complicated How many unique strings could be inserted into the trie without using any additional memory? (Do not include an empty or null string) How many nodes are being reused in the trie? Suppose we call an insertstring function on the node representing the r in computer. What is maximum length of a string we can insert there without increasing the height of the main trie? What is the best and worst case runtimes for insertion, access, and deletion in a trie? Best Worst Insertion Access Insertion What is the advantage and the disadvantage of using a trie vs a hash table to store the frequency of words in a given text file?

3 Page 3 Insert the following values into a MinHeap in order. Show what the MinHeap looks like after each insertion. Insert: 19, 7, 12, 20, 4, 1, 14, 3, 24, 6

4 Page 4 What are the guaranteed characteristics of a min/max heap? What is the best and worst case runtime for insertion and deletion from a heap? What causes our runtime to go down from this best case? Insertion Deletion In the following MinHeap, what values could we insert into it in order to achieve the best and worst-case runtimes? Best Worst What sorting algorithm functions similarly to HeapSort? Which one is better? Why?

5 Use the following hash function along with the specified probing method to insert the given values into the provided hash tables. Page 5 int hash(int key, int size) { return ((key - 20) * 5) % size; } Using linear probing Insert: 56, 41, 65, 22, 37, 48 Index Value Using quadratic probing Insert: 40, 57, 91, 31, 25, 20 Index Value Using separate chaining Use the area under the table to make any necessary linked lists Insert: 21, 41, 25, 31, 27, 38, 44, 36, 30, 23, 32 Index Value What are the requirements to be able to use quadratic probing? What is the advantage and the disadvantage of using separate chaining?

6 Page 6 Convert the following numbers from to the given base > binary > base > hexadecimal >binary >decimal > base > base > hexadecimal

7 Page 7 Evaluate each of the following expressions: (34 & 42) ^ 11 = (22 51) & 25= (19 ^ 23) << 2 = ~((15 << 3) 23) =

8 Page 8 What are the basic components of a backtracking algorithm? If we were to use backtracking to solve for all possible solutions to a sudoku puzzle, what might we check for in our base cases? In what situation do we not have to check for duplicate states when writing a backtracking algorithm?

9 Page 9 Perform one pass of the following sorting algorithms on the given arrays QuickSort: RadixSort: Given the following array before and after a single pass of a sorting algorithm, identify which algorithm(s) could have been used Fill in the array to create a worst-case runtime for quicksort Which of the following sorting algorithms has the best worst-case space complexity? CountingSort MergeSort Radix Sort Selection Sort

10 Page 10 If we implement a stack using a linkedlist, what is the best and worst case runtimes for push and pop? Push Pop Best Worst When implementing a queue as a linkedlist, should we maintain a tail pointer? Why? What are the steps to insert an item between two elements in a linkedlist?

11 Page 11 General Tips: Be VERY familiar with linkedlists and trees, since many data structures are based off their principles Don t just memorize, but instead understand the big O runtimes for all the sorts and data structures. Once you can understand the reasoning there is no need to memorize all the runtimes Practice writing a function for each of the data structures discussed in class Topics discussed in this class are the foundation for many other classes going forward, do not ignore them Videos and guides online are a great resource for topics you don t understand For any coding problems, always write something! Even just putting something such as base cases can really help to earn you extra points. Useful Resources: Visualizer for many of the data structures discussed in class: Link Big O runtime cheat sheet: Link Dr. Guha s CS1 archive: Link LeetCode practice problems (filter by topic and easy difficulty): Link