1. Regarding homework 9 Many low grades
To recover half of the points lost on Map methods
Download test program used (from home page)
Fix any problem(s)
Bring to lab on Friday may 5
Original code with attached grading sheet
Hard copy of revised map.cpp with changed or added code highlighted
Run your program with provided test case for one of the instructors
Be ready to answer questions about the changes you made

2. Using a vector to store the vertices
What is the efficiency of getvnum(vname)
O(n)
What is the efficiency of getvname(vnum)
O(1)

3. How many edges does a graph with v vertices have?

4. Storing the edges A graph has between 0 and v2 edges
Adjacency matrix based on storing information about all possible edges
Adjacency list based on storing information about only the existing edges

5. Storing the edges of a graph

6. Vertex table 1 2 3 4 A B C D E 1 2 3 4 1 2 3 4 1 2 3 4
Adjacency list
Adjacency matrix

7. Vertex table 1 2 3 4 A B C D E 1 2 3 4 1 2 3 4 1 2 4 2 1 2 3 4 1 1 3 2
Adjacency list
Adjacency matrix

8. Storing the edges of a digraph

9. 0 A
1 B
2 C
3 D
4 E

10. 0 A 1 B 2 C 3 D 4 E How do we find out if v1 is adjacent to v2?
How do we find out if v1 is adjacent from v2?

11. Comparing adjacency matrix and adjacency lists
Given that a graph has v vertices and e edges
How much memory space is needed?
What is the efficiency of
Add an edge from v1 to v2?
Is there an edge from v1 to v2?
How many vertices are adjacent to v1?
How many vertices are adjacent from v1?

12. standard template library (STL)
Most programs need to store a collection of like elements
Most programming languages now have types (classes) that programmers can use
Java: collection classes
Python: list and map
C++ added the standard template library in 1998
Stl was updated in 2011 and 2014

13. Stl components
Containers iterators algorithms

14. containers
Are templates for classes that hold a collection of like items
a class to hold a specific type can be created from a template
User of the class decides type of items to be stored
Alternative to using typedef to define the type of items
Ex: vector<t> is a template
<T> is a type parameter that needs to replaced with a specific type
vector<int> numbers;
vector<string> words;

15. Any questions about homework 10?

16. Some Stl containers Sequence containers Vector List
Forward_list - added in 2011
Container adapters
Stack
Queue
PRIORITy_queue
Associative containers
Map
Set
Unordered associative containers
Unordered_map - added in 2011
Unordered_set - added in 2011

17. Sequence container classes share many methods

18. Using stl container classes to implement a graph
Vertex table
Vector<string>;
Adjacency matrix
vector<vector<bool>> edges;
Adjacency lists
???

19. Using stl container classes to implement a graph
Vertex table
Vector<string>;
Adjacency matrix
vector<vector<bool>> edges;
Adjacency lists
Vector<vector<int>> edges;
Vector<list<int>> edges;
Vector<forward_list<int> edges;
Which is best? and why?

20. iterators
Stl container classes have iterator classes associated with them
Ex: <vector> defines a type: vector<T>::iterator
<list> defines a type: list<t>::iterator
An iterator provides access to an element in a container
Provide same functionality as vector indices and linked list node pointers
Iterator objects associated with all container classes have 3 methods
Iter // iter now gives access to the “next” element
*iter // the value of the element accessed by iter
== and !== // do two iterators access the same element?
Iterator objects associated with some container classes have additional methods
Iterators associated with which sequence container class can be decremented?

21. How are iterators used?
Moving through a container one element at a time
all container classes (except adapters like stack and queue) have two methods
Begin() // returns an iterator that accesses the container’s first element
End() // returns an iterator that is positioned after the container’s last element
Dereferencing it is an error
Vector<string> words; // add strings to words vector<string>::iterator iter = words.begin(); // or auto iter = words.begin(); for (iter; iter != words.end(); iter++) { cout << *iter << endl; }
Suppose words was defined as: forward_list<string>
Iterators are the connection between containers and algorithms

22. <algorithm>
Contains functions that operate on a range of elements in a container
The range is defined by iterators
Ex: words.Begin() and words.end() specifies all elements in words
Some functions defined in <algorithm>
Find
Find_if
min_element
For_each
Sort

23. Using sort
Can only be used with containers that have random access iterators
Two parameter version
Iterators specifying range of elements to sort
Uses < operator to compare elements
Three parameter version
Third parameter is a function that compares 2 elements