from Edge import Edge

from DirectedGraph import DirectedGraph

from AdjacencyListVertex import AdjacencyListVertex

class AdjacencyListGraph$($DirectedGraph$)$:

def $\_\_$init$\_\_($self$)$:

self.vertices $=[]$

self.adjacency$\_$list $=\{\}$

# Creates and adds a new vertex to the graph, provided a vertex with the

# same label doesn't already exist in the graph. Returns the new vertex on

# success, None on failure.

def add$\_$vertex$($self$,$ new$\_$vertex$\_$label$)$:

if new$\_$vertex$\_$label in self.adjacency$\_$list:

return None # Vertex already exists

new$\_$vertex $=$ AdjacencyListVertex$($new$\_$vertex$\_$label$)$

self.vertices.append$($new$\_$vertex$)$

self.adjacency$\_$list$[$new$\_$vertex$\_$label$]=[]$

return new$\_$vertex

# Adds a directed edge from the first to the second vertex. If the edge

# already exists in the graph, no change is made and False is returned.

# Otherwise the new edge is added and True is returned.

def add$\_$directed$\_$edge$($self$,$ from$\_$vertex, to$\_$vertex$)$:

if from$\_$vertex not in self.adjacency$\_$list or to$\_$vertex not in self.adjacency$\_$list:

return False # One or both vertices do not exist

if to$\_$vertex in self.adjacency$\_$list$[$from$\_$vertex$]$:

return False # Edge already exists

self.adjacency$\_$list$[$from$\_$vertex$].$append$($to$\_$vertex$)$

return True

# Returns a list of edges with the specified from$\_$vertex.

def get$\_$edges$\_$from$($self$,$ from$\_$vertex$)$:

if from$\_$vertex not in self.adjacency$\_$list:

return $[]$ # No such vertex

from$\_$vertex$\_$obj $=$ self.get$\_$vertex$($from$\_$vertex$)$

return $[$Edge$($from$\_$vertex$\_$obj, self.get$\_$vertex$($to$\_$vertex$))$ for to$\_$vertex in self.adjacency$\_$list$[$from$\_$vertex$]]$

# Returns a list of edges with the specified to$\_$vertex.

def get$\_$edges$\_$to$($self$,$ to$\_$vertex$)$:

if to$\_$vertex not in self.adjacency$\_$list:

return $[]$ # No such vertex

to$\_$vertex$\_$obj $=$ self.get$\_$vertex$($to$\_$vertex$)$

edges$\_$to $=[]$

for from$\_$vertex in self.adjacency$\_$list:

if to$\_$vertex in self.adjacency$\_$list$[$from$\_$vertex$]$:

edges$\_$to$.$append$($Edge$($self$.$get$\_$vertex$($from$\_$vertex$),$ to$\_$vertex$\_$obj$))$

return edges$\_$to

# Returns a vertex with a matching label, or None if no such vertex exists

def get$\_$vertex$($self$,$ vertex$\_$label$)$:

for vertex in self.vertices:

if vertex.get$\_$label$()==$ vertex$\_$label:

return vertex

return None

# Returns True if the graph has an edge from from$\_$vertex to to$\_$vertex

def has$\_$edge$($self$,$ from$\_$vertex, to$\_$vertex$)$:

if from$\_$vertex not in self.adjacency$\_$list or to$\_$vertex not in self.adjacency$\_$list:

return False

return to$\_$vertex in self.adjacency$\_$list$[$from$\_$vertex$]$

$\text{'}\text{'}\text{'}$

from Edge import Edge

from DirectedGraph import DirectedGraph

from AdjacencyListVertex import AdjacencyListVertex

class AdjacencyListGraph$($DirectedGraph$)$:

def $\_\_$init$\_\_($self$)$:

self.vertices $=[]$

# Creates and adds a new vertex to the graph, provided a vertex with the

# same label doesn't already exist in the graph. Returns the new vertex on

# success, None on failure.

def add$\_$vertex$($self$,$ new$\_$vertex$\_$label$)$:

# Your code here $($remove placeholder line below$)$

pass

# Adds a directed edge from the first to the second vertex. If the edge

# already exists in the graph, no change is made and False is returned.

# Otherwise the new edge is added and True is returned.

def add$\_$directed$\_$edge$($self$,$ from$\_$vertex, to$\_$vertex$)$:

# Your code here $($remove placeholder line below$)$

pass

# Returns a list of edges with the specified from$\_$vertex.

def get$\_$edges$\_$from$($self$,$ from$\_$vertex$)$:

# Your code here $($remove placeholder line below$)$

pass

# Returns a list of edges with the specified to$\_$vertex.

def get$\_$edges$\_$to$($self$,$ to$\_$vertex$)$:

# Your code here $($remove placeholder line below$)$

pass

# Returns a vertex with a matching label, or None if no such vertex exists

def get$\_$vertex$($self$,$ vertex$\_$label$)$:

# Your code here $($remove placeholder line below$)$

pass

# Returns True if self graph has an edge from from$\_$vertex to to$\_$vertex

def has$\_$edge$($self$,$ from$\_$vertex, to$\_$vertex$)$:

# Your code here $($remove placeholder line below$)$

pass

$\text{'}\text{'}\text{'}$ this code is outputting: AdjacencyListGraph:

PASS: add$\_$vertex$("$A$")$ returned a vertex

PASS: add$\_$vertex$("$B$")$ returned a vertex

PASS: get$\_$vertex$("$C$")$ returned None

PASS: get$\_$vertex$("$A$")$ returned a vertex with a correct label

PASS: get$\_$vertex$("$B$")$ returned a vertex with a correct label

PASS: get$\_$vertex$("$E$")$ returned None please modify adjacencylist.graph for it to pass these test. here isdirectggraph.py: