1. priority_queue<T>
More on the C++ STL
vector<T>
list<T>
stack<T>
queue<T>
priority_queue<T>

2. STL Container Classes
Sequence containers organize items by position: 1st, 2nd, 3rd, …., last
vector, list, deque
Adapter containers are restricted versions of other containers
stack, queue, priority_queue
Associative containers organize items based on a key value
set, map, multiset, multimap

3. vector<T> vs. list<T>
can expand to hold as many items as needed
O(1) insert/delete at end of the list
O(n) insert/delete at position i in the list
indexing (vec[i]) gives gives O(1) access to any position
list<T>
can expand to hold as many items as needed
O(1) delete of any item
O(1) insert before any item
no indexing – cannot access item at position i in O(1)

4. Use different storage structures
vector<T> items stored in an array (contiguous storage) 1 2 3 4 5 6 7 8 9 10 11
list<T> items stored in a linked list (non-contiguous storage) 1 2 3 4 5 6 7 8

5. Partial list<T> API
list() //construct an empty list
push_back(item) //add item at end of list
pop_back() //remove item at end of list
push_front(item) //add item at front of list
pop_front() //remove item at front of list
size() //return number of items in list
back() //return item at end of list
front() //return item at front of list

6. STL iterators an iterator is a generalization of a pointer
used to access an element in the container
each STL container class has a nested iterator class associated with it
vector<T>::iterator
list<T>::iterator
STL container classes have methods which return iterators
begin() //returns an iterator accessing first element
end() //returns an iterator that is past the last //element

7. iterator operations iter++ //access next element
iter //access prior element
== and != //compare 2 iterators
*iter //dereference the iterator

8. An Example list<int> myList; // store some items in myList
list<int>::iterator iter;
iter = myList.begin();
while (iter != myList.end()) {
//process *iter
iter++; }

9. STL Components
Container classes - templates for classes which hold a collection of elements
Algorithms - templates for functions which operate on a range of elements from a container
range is specified by iterators
Iterators
give access to the element in a container
allow for movement from one element to another
Container Classes
Algorithms
Iterators

10. STL Algorithms
designed to operate on a sequence of elements rather than on a specific container
the sequence is designated by two iterators
all container classes have the following two methods
begin( ) returns an iterator positioned at the container's first element
end( ) returns an iterator positioned past the container's last element (past-the-end)
C.begin( ), C.end( ) specifies a sequence which contains all elements of the container C

11. STL Algorithms some examples of STL algorithms
find(iter1, iter2, value) //returns an iterator
max_element(iter1, iter2) //returns an iterator
sort(iter1, iter2) //sorts using <
for_each(iter1, iter2, F) //applies F to every //item
see STL Programmer's Guide link on home page

12. Using iterators #include <iostream> #include <vector>
#include <algorithm>
#include <cstdlib>
using namespace std; void set(int & val); void display(int val);
void main( ) { vector<int> A(5);
for_each(A.begin( ), A.end( ), set); // will not work w/ vector<int> A;
for_each(A.begin( ), A.end( ), display);
cout << endl;
sort(A.begin( ), A.end( )); // operator< must be defined for A's element type }
void set(int & val) { val = rand( ); }
void display(int val) { cout << " " << val; }