1. Stacks
A list where insertions and deletions can occur only at the end of the list.
linked list or array implementation
topOfStack  33 -4 8 10
127 5
operations:
push (insert)
pop (remove)
topAndPop
Oct 17, 2001
CSE 373, Autumn 2001

2. Stack Applications calculators: postfix or reverse Polish notation.
example: *
Function calls
stack frame or activation record
func4
return var
locals vars
arguments
func2
func1
func1() {
func2();
func3(); }
func2() {
func4(); }
Oct 17, 2001
CSE 373, Autumn 2001

3. Queues A list where circular array (modular arithmetic)
inserts happens at the end
removes happen at the beginning
circular array (modular arithmetic)
Applications: graph algs, operating systems, web servers, etc. 5 3 7 ^^
front
back -5 4 8 2 1 ^^
back
front
Oct 17, 2001
CSE 373, Autumn 2001

4. Trees Motivation: O(N) time to access arrays or linked lists.
Goal: O(log N) time for all operations.
A tree is a collection of nodes. The collection may be empty. If it isn’t empty, then the tree consists of a distinguished node r, called a root and zero or more non-empty distinct (sub)trees T1, … , Tk, each of whose root are connected by a directed edge from r.
Oct 17, 2001
CSE 373, Autumn 2001

5. Visualizing Trees root of each subtree is a child of r.
r is the parent of each subtree root. r T2 T3 T1
Oct 17, 2001
CSE 373, Autumn 2001

6. Tree terminology A leaf has no children.
Siblings have the same parent.
grandparent, grandchild
A path is a sequence of nodes n1, n2, … , nk such that ni is the parent of ni+1 for 1  i < k.
The length of a path is the number of edges in the path.
The depth of a node is the length of the path from the root to the node.
The height of a tree: length of the longest path from root to a leaf.
Oct 17, 2001
CSE 373, Autumn 2001

7. Tree example C:\ MyMail D101 cse373 school pers hw1 hw2 proj1 coll.h
coll.cpp
poly.h
Oct 17, 2001
CSE 373, Autumn 2001