Adjacency  Matrix  Topological  Order   Iterator   import  java.io.*;   import  java.uFl.*;   public  class  AdjMatrixGraph  {    int  g[][];    private  int  indegree[];    private  String  vertexNames[];    private  int  numNodes;   Adjacency  Matrix  Topological  Order   Iterator    public  AdjMatrixGraph(String  filename)  {      BufferedReader  b  =  null;      try  {        b  =  new  BufferedReader(new  FileReader(filename));        numNodes  =  Integer.parseInt(b.readLine());      }      catch  (ExcepFon  e)  {        System.out.println("Error  in  file  contents  or  file  not  found");      }        g  =  new  int[numNodes][numNodes];      vertexNames  =  new  String[numNodes];   Adjacency  Matrix  Topological  Order   Iterator      try  {        for  (int  i  =  0;  i  <  numNodes;  i++)          vertexNames[i]  =  b.readLine();        String  line  =  b.readLine();        while  (line  !=  null)  {          Scanner  s  =  new  Scanner(line);          int  v1  =  getNodeNum(s.next());          int  v2  =  getNodeNum(s.next());          g[v1][v2]  =  1;          line  =  b.readLine();        }      }      catch  (ExcepFon  e)  {          System.out.println("Error  in  file  contents"+e.getMessage());      }    }   Adjacency  Matrix  Topological  Order   Iterator    private  int  getNodeNum(String  v)  {      for  (int  i  =  0;  i  <  numNodes;  i++)        if  (vertexNames[i].equals(v))          return  i;      return  -­‐1;    }      private  void  iniFalizeIndegree()  {      for  (int  i  =  0;  i  <  numNodes;  i++)  indegree[i]  =  0;        for  (int  j  =  0;  j  <  numNodes;  j++)          for  (int  i  =  0;  i  <  numNodes;  i++)          indegree[j]  =  indegree[j]+g[i][j];    }   Adjacency  Matrix  Topological  Order   Iterator    public  class  TopoIterator  implements  Iterator<String>  {      private  Queue<Integer>  nodeQueue;      public  TopoIterator()  {        indegree  =  new  int[numNodes];        iniFalizeIndegree();        nodeQueue  =  new  LinkedList<Integer>();        for  (int  i  =  0;  i  <  numNodes;  i++)            if  (indegree[i]  ==  0)     .

1. Adjacency
Matrix
Topological
Order
Iterator
import
java.io.*;
import
java.uFl.*;
public
class
AdjMatrixGraph
{
int
g[][];
private
int
indegree[];

2. private
String
vertexNames[];
private
int
numNodes;
Adjacency
Matrix
Topological
Order
Iterator
public
AdjMatrixGraph(String
filename)
{
BufferedReader
b
=
null;
try

3. {
b
=
new
BufferedReader(new
FileReader(filename));
numNodes
=
Integer.parseInt(b.readLine());
}
catch
(ExcepFon
e)
{
System.out.println("Error
in
file
contents

4. or
file
not
found");
}
g
=
new
int[numNodes][numNodes];
vertexNames
=
new
String[numNodes];
Adjacency
Matrix
Topological
Order
Iterator

5. try
{
for
(int
i
=
0;
i
<
numNodes;
i++)
vertexNames[i]
=
b.readLine();
String
line
=
b.readLine();

6. while
(line
!=
null)
{
Scanner
s
=
new
Scanner(line);
int
v1
=
getNodeNum(s.next());
int
v2
=
getNodeNum(s.next());

7. g[v1][v2]
=
1;
line
=
b.readLine();
}
}
catch
(ExcepFon
e)
{

8. System.out.println("Error
in
file
contents"+e.getMessage());
}
}
Adjacency
Matrix
Topological
Order
Iterator
private
int
getNodeNum(String
v)
{
for
(int
i
=

9. 0;
i
<
numNodes;
i++)
if
(vertexNames[i].equals(v))
return
i;
return
-­‐1;
}
private
void
iniFalizeIndegree()
{

10. for
(int
i
=
0;
i
<
numNodes;
i++)
indegree[i]
=
0;
for
(int
j
=
0;
j
<
numNodes;
j++)
for
(int

11. i
=
0;
i
<
numNodes;
i++)
indegree[j]
=
indegree[j]+g[i][j];
}
Adjacency
Matrix
Topological
Order
Iterator
public
class
TopoIterator
implements
Iterator<String>

12. {
private
Queue<Integer>
nodeQueue;
public
TopoIterator()
{
indegree
=
new
int[numNodes];
iniFalizeIndegree();
nodeQueue
=
new
LinkedList<Integer>();

13. for
(int
i
=
0;
i
<
numNodes;
i++)
if
(indegree[i]
==
0)
nodeQueue.offer(i);
}

14. Adjacency
Matrix
Topological
Order
Iterator
private
void
updateIndegree(int
v)
{
for
(int
i
=
0;
i
<
numNodes;
i++)
{

15. if
(g[v][i]
==
1)
{
indegree[i]-­‐-­‐;
if
(indegree[i]
==
0)
nodeQueue.offer(i);
}

16. }
}
Adjacency
Matrix
Topological
Order
Iterator
public
boolean
hasNext()
{
return
!nodeQueue.isEmpty();

17. }
public
String
next()
{
int
v
=
nodeQueue.poll();
String
nodeName
=
vertexNames[v];
updateIndegree(v);

18. return
nodeName;
}
public
void
remove()
{
//opFonal
method
not
implemented
throw
new
UnsupportedOperaFonExcepFon();
}

19. }
Adjacency
Matrix
Topological
Order
Iterator
public
Iterator<String>
iterator()
{
//return
a
new
iterator
object
return
new
TopoIterator();
}

20. public
int
order()
{
return
numNodes;
}
public
staFc
void
main(String
args[])
{
AdjMatrixGraph
g1
=
new
AdjMatrixGraph(args[0]);

21. Iterator<String>
topo
=
g1.iterator();
while
(topo.hasNext())
{
System.out.println(topo.next()+'t');
}
}
}
Input
File
Format
• The

22. representaFon
of
a
graph
in
the
file
contains
the
following
informaFon.
A
line
containing
an
integer,
n,
where
n
is
the
number
of
nodes
in
the
graph.
A
sequence
of
n
lines
each

23. of
which
contains
a
name
associated
with
a
node.
The
names
will
only
contains
lejers
and
digits.
Following
the
names
will
be
one
line
for
each
edge.
An
edge
will
be
represented

24. by
a
pair
of
names
separated
by
a
space.
On
the
next
slide
is
an
example
Input
File
Format
8
A
B
C
D

25. E
F
G
H
A
B
A
C
B
E
B
D
C
D
C
F
F
G
E
H
E
G
D

26. G
Assignment
3
• Implement
a
class
called
AdjListGraph
that
is
similar
to
the
AdjMatrixGraph.
• AdjListGraph
must
store
a
graph
using
an
adjacency
list
representaFon

27. • The
constructor
for
AdjListGraph
has
the
same
signature
as
the
constructor
for
AdjMatrixGraph.
• The
input
file
format
used
by
AdjListGraph
is
the
same
of
as
AdjMatrixGraph

28. Assignment
3
• AdjListGraph
must
implement
an
iterator
that
can
provides
node
names
in
topological
order.
• The
following
two
slides
give
a
template
of
the
class.
• Use
LinkedList
objects

29. for
the
adjacency
lists
• Since
you
are
given
the
number
of
nodes
you
can
use
an
array
of
LinkedList
objects
to
store
all
the
adjacency
lists
• You
can
add
other
methods

30. as
needed
• Do
not
change
the
main
method
Assignment
3
import
java.io.*;
import
java.uFl.*;
public
class
AdjListGraph
{
public
AdjListGraph(String
filename)

31. {
}
public
class
TopoIterator
implements
Iterator<String>
{
public
TopoIterator()
{
}
public
boolean
hasNext()
{
}

32. public
String
next()
{
}
public
void
remove()
{
//opFonal
method
not
implemented
throw
new
UnsupportedOperaFonExcepFon();
}
}

33. Assignment
3
public
Iterator<String>
iterator()
{
}
public
int
order()
{
}
public
staFc
void
main(String
args[])
{

34. int
count
=
0;
AdjListGraph
g1
=
new
AdjListGraph(args[0]);
Iterator<String>
topo
=
g1.iterator();
while
(topo.hasNext())
{
count++;
System.out.println(topo.next()+'t');

35. }
if
(count
!=
g1.order())
System.out.println("The
graph
does
not
have
a
topological
order");
}
}
•