Node and Edge Functions

• `add node`: will add a node to the graph with the given value if our graph still has room. Finding a location for the node will be the same procedure as the matrix graph. If we find an open spot to add the node, we will instantiate a new graph node and insert it into the `nodes` attribute.
``````function ADDNODE(VALUE)
IDX = -1
for NODE in NODES
if NODE is VALUE
return NODE's index
if NODE has no entry and IDX is -1
IDX = NODE's index
if IDX is not -1
NEWNODE = graph node with VALUE and IDX for input
add NEWNODE to NODES at position IDX
increment SIZE
return IDX``````
• `remove node`: will remove a node to the graph with the given value if our graph has the node. We will set the node to be empty. When we set the node to be empty, we clear all of the outgoing edges, so we just need to loop through the other nodes removing any possible incoming edges.
``````function REMOVENODE(IDX)
if IDX is in the range of our indexes
if NODES at position IDX is not empty
set NODES at IDX to be empty
decrement SIZE by one
for NODE in NODES
if NODE has no entry
from NODE call the graph node REMOVEEDGE function on IDX
return true
else
return false
else
return false ``````
• `add edge`: will add an edge with the given weight which goes from the source node to the target node
``````function ADDEDGE(SRC, TAR, WEIGHT)
if SOURCE and TARGET are both in the range of our node indexes
SRCNODE = the node at index SRC of the NODES attribute
if SRCNODE is not empty
from SRCNODE call the graph node ADDEDGE with TAR and WEIGHT as input
return true
else
return false
else
return false``````
• `remove edge`: will remove the edge which goes from the source node to the target node
``````function REMOVEEDGE(SOURCE, TARGET)
if SOURCE and TARGET are both in the range of our node indexes
SRCNODE = the node at index SRC of the NODES attribute
if SRCNODE has no entry
RET = SRCNODE call the graph node REMOVEEDGE with TAR as input
return RET
else
return false
else
return false``````
• `add undirected edge`: will add two edges with the given weight between the two given nodes
``````function ADDUNDIRECTEDEDGE(NODE1, NODE2, WEIGHT)
RES = RES and ADDEDGE(NODE2, NODE1, WEIGHT)
return RES``````
• `remove undirected edge`: will remove two edges between the two given nodes.
``````function REMOVEUNDIRECTEDEDGE(NODE1, NODE2)
RES = REMOVEEDGE(NODE1, NODE2)
RES = RES and REMOVEEDGE(NODE2, NODE1)
return RES``````