CS315 Notes

CS315 Class Notes

Raphael Finkel

May 4, 2021

Intro

Class 1, 1/26/2021

• Handout 1 — My names
• TA: Patrick Shepherd
• Plagiarism — read aloud
• Assignments on web. Use C, C++, or Java.
• accounts in MultiLab
• text — we will skip around

Basic building blocks: Linked lists (Chapter 3)

and trees (Chapter 4)

Linked lists and trees are examples of data structures:

• way to represent information
• so it can be manipulated
• packaged with routines that do the manipulations

Leads to an Abstract Data Type (ADT): has an API (specification) and hides its internals.

Tools · Use · Implementation · Specification · Singly-linked list

• used as a part of several ADTs.
• Can be considered an ADT itself.
• Collection of nodes, each with optional arbitrary data and a pointer to the next element on the list.

a · c · x · f · handle · data · null pointer · pointer · operation · cost

create empty list O(1) insert new node at front of list O(1) delete first node, returning data O(1) count length O(n) search by data O(n) sort O(n log n) to O(n2)

Sample code (in C)

1 #define NULL 0

4 typedef struct node_s { int data; struct node_s *next; 7 } node;

9 node *makeNode(int data, node* next) { node *answer = (node *) malloc(sizeof(node));

Answer: >data = data;

Answer: >next = next;

14 } // makeNode

16 node *insertAtFront(node* handle, int data) { node *answer = makeNode(data, handle->next); handle->next = answer;

20 } // insertAtFront

22 node *searchDataIterative(node *handle, int data) {

node *current = handle->next; while (current != NULL) { if (current->data == data) break;

return current;

32 node *searchDataRecursive(node *handle, int data) { // recursive method node *current = handle->next; if (current == NULL) return NULL; else if (current->data == data) return current; else return searchDataRecursive(current, data); 38 } // searchDataRecursive