def roadsAndLibraries(n, c_lib, c_road, cities):
# Complete this function
if not n:
return 0
if c_lib <= c_road:
return n * c_lib
graph = Graph()
# for _n in range(n):
# graph.addVertex(Vertex(str(_n+1)))
for edge in cities:
try:
graph.addVertex(Vertex(str(edge[0])))
except KeyError:
pass
try:
graph.addVertex(Vertex(str(edge[1])))
except KeyError:
pass
graph.createEdge(str(edge[0]), str(edge[1]))
print graph.degree
subgraphs = graph.listSubGraphs()
print subgraphs
libraries = len(subgraphs) + (n - graph.degree)
roads = 0
for g in subgraphs:
roads += len(g) - 1
return (libraries * c_lib) + (roads * c_road)
def prims(graph, start):
print("Finding minimum spanning tree")
graph.print()
minSpanTree = Graph()
heap = EdgeMinHeap()
visited = dict()
for vertex in graph.getVertices():
visited[vertex] = False
minSpanTree.addVertex(start)
visited[start] = True
print("Adding edges adjacent to initial vertex to potential edges")
for edge in graph.getAdjEdges(start):
heap.siftUp(edge[0], edge[1], edge[2])
heap.print()
done = heap.isEmpty()
while not done:
print("Sifting down to find shortest edge with an unvisited destination")
heap.print()
top = heap.siftDown()
found = not visited[top[1]] # top.to
done = heap.isEmpty()
heap.print()
while not found and not done:
top = heap.siftDown()
found = not visited[top[1]]
heap.print()
if heap.isEmpty():
done = True
if not found:
break
print(str(top) + " is a valid edge. Adding to MST")
visited[top[1]] = True
minSpanTree.addVertex(top[1])
minSpanTree.addEdge(top[0], top[1], top[2])
print("Adding edges adjacent to " + str(top[1]) + " to potential edges")
for edge in graph.getAdjEdges(top[1]):
if not visited[edge[1]]:
heap.siftUp(edge[0], edge[1], edge[2])
heap.print()
return minSpanTree
from graphs import Graph, Vertex, Edge
graph = Graph()
for n in '123456':
graph.addVertex(Vertex(n))
graph.createEdge('1', '2')
graph.createEdge('1', '3')
graph.createEdge('2', '3')
graph.createEdge('2', '4')
graph.createEdge('3', '4')
graph.createEdge('5', '6')
print graph.listSubGraphs()
