Question

def prim(G): Use Prim's algorithm to find a MST for the graph G … # Initialize tree T with a single vertex and no edges v = next(iter( )) # while the vertex set of T is smaller than the v+tex set of G, # (i.e. while the vertex set of T is a proper subset of the vertex set of G), find the edge e with minimum weight so that # Tte is a tree. Then update T T+e ''' # return T

need help filling in the code

Answer 1

Since you have not provided the implementation of G (What does G represent here), I have assumed that G consists of an adjacency matrix and a function to get the number of vertices in the graph.

CODE

def prims(G):

# arbitrarily choose initial vertex from graph

vertex = 0

# initialize empty edges array and empty MST

MST = []

edges = []

visited = []

minEdge = [None,None,float('inf')]

V = G.getVertexCount()

# run prims algorithm until we create an MST

# that contains every vertex from the graph

while len(MST) != V-1:

# mark this vertex as visited

visited.append(vertex)

# add each edge to list of potential edges

for r in range(0, V):

if G.adjMatrix[vertex][r] != 0:

edges.append([vertex,r,G.adjMatrix[vertex][r]])

# find edge with the smallest weight to a vertex

# that has not yet been visited

for e in range(0, len(edges)):

if edges[e][2] < minEdge[2] and edges[e][1] not in visited:

minEdge = edges[e]

# remove min weight edge from list of edges

edges.remove(minEdge)

# push min edge to MST

MST.append(minEdge)

# start at new vertex and reset min edge

vertex = minEdge[1]

minEdge = [None,None,float('inf')]

return MST

1 def prims (G): # arbit rarily choose initial vertex from graph vertex0 4 # initialize empty edges array and empty MST MST [ edges visited[ minEdge[None,None, float( 'inf')] V G.getVertexCount () # run prims algorithm until we create an MST # that contains every vertex from the graph while len (MST)-V-1: 12 15 # mark this vertex as visited visited.append (vertex) # add each edge to list of potential edges for r in range(0, v): 18 19 if G.adjMatrix[vertex] [r]0: edges.append ( [vertex,r,G.adjMatrix[vertex][r]]) 23 # find edge with the smallest weight to a vertex # that has not yet been visited for e in range(0, len(edges)): 25 26 27 if edges [e] [2 minEdge [2] and edges [e] [1] not in visited: minEdge -edges [el # remove min weight edge from list of edges edges.remove (minEdge) # push min edge to MST MST.append (minEdge) # start at new ve rtex and reset min edge vertex minEdge [1] minEdge [None ,None, float(' inf')] 29 31 32 34 35 return MST