Abstract Data Types – ADTs

Object-Oriented Paradigm

	World consists of objects/components and their interactions with each other
	Goal is to be able to have proven, tested software components that are reusable, won’t have to write all code from scratch – speed software development
	Came out of Simulation – Simula first OO language
	Encapsulation, Inheritance, Polymorphism

Standard Template Library - STL

	Why – save time, don’t reinvent the wheel!
	Three generic entities:
	Container – a data structure that organizes objects a specific way, e.g. stack, queue, vector, list
	Iterators – object used to reference an element in
	a container, like a pointer, just for some containers like list
	Algorithms – frequently used functions on containers – e.g. make-heap, find_first, sort  ( Appendix B Drozdek)

Complexity of algorithms – Big “O”

	Used to look at time and space complexity – now just time
	As the size of the data set grows, how does the time the algorithm takes to run grow?
	In a formula, take fastest growing term, ignore constant multipliers

More on Big “O”

	Usually use “n” as the variable to denote size of the data set
	If have expression for run-time complexity
		F(n) = 7 e**n + 100 n **2 + 250 n + 1,000,000
		Dominant term above, as n grows large is?

Big “O”, continued

Review - simple data structures

	STL vectors
	Lists
	Stacks
	Queues

VECTORS – dynamically sized

LISTS

	#include <list>
	list<int> iList ; iList.push_front(5); iList.pop_back();
	list<char> cList;                      cList.clear(); if(cList.empty()) ….
	list<anyClass> acList; int size=acList.size();

STACKS – LIFO lists

	#include <stack>
	stack<int> iStack       iStack.push(5);
	stack<char> cStack;  cStack.pop();
	stack<anyClass> acStack;

QUEUES – FIFO lists

RECURSION

	A problem solving tool as well as a feature incorporated in programming languages
	Recursive problems have two features
	Solutions are easy to give for special states (stopping states)
	For a given state (not a stopping state) there are clear rules for how to proceed to a new state.  This new state is either
	a) a stopping state b) leads to a stopping state

"What goes on in memory..."

	What goes on in memory with a recursive call?
	With each recursive call a local environment (or stack frame) is stacked which includes enough storage for:
	1) LOCAL VARIABLES
	2) VALUE PARAMETERS
	3) REFERENCES (POINTERS) BACK TO CALL-BY-     REFERENCE PARAMETERS
	4) CELL FOR PASSING BACK THE VALUE OF THE      FUNCTION (FOR NON-VOID FUNCTIONS)
	5) THE ADDRESS TO RETURN TO AFTER COMPLETING     THE EXECUTION OF THE CURRENT RECURSIVE CALL

"Recursion exemplifies DIVIDE AND CONQUER"

	Recursion exemplifies DIVIDE AND CONQUER  problem-solving strategies ---
	Example: TOWERS OF HANOI - 19th century parlor game with 64 disks
	Object: Move all disks from peg1 to peg3 using peg2 for intermediate storage
	Rules: One disk moved at a time, and a disk can never rest on a smaller disk

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