def BFS(self, v):
""" Runs breadth-first search from the source vertex v. Returns a matrix with distances from v, or None if v does not exist. """
if v >= self.vertexCount():
return None # can't be run; vertex doesn't exist
# initialize the vertex queue, the "visited" set s, and the distances from v
q = MinHeap()
s = set()
distance = [float("inf")] * self.vertexCount()
# insert the source vertex into q and set its distance as 0
q.insert(KeyValuePair(0, v))
s.add(v)
distance[v] = 0
# loop through all vertices, in order of distance from v, relaxing edges out of current vertex
kvp = q.extractMin()
while kvp:
v = kvp.value
d = kvp.key
# relax all edges out of current vertex v
edges = self._adj[v]
for e in edges:
if e.dest not in s:
s.add(e.dest)
distance[e.dest] = d + 1
q.insert(KeyValuePair(distance[e.dest], e.dest))
# get next-lowest distance vertex
kvp = q.extractMin()
return distance
def test1():
minhp = MinHeap()
for idx in range(10):
minhp.add(idx + 1)
minhp.add(20 - idx)
minhp.printer()
for idx in range(20):
print minhp.extractMin()
def test2():
minhp = MinHeap()
print minhp.isEmpty()
minhp.add(1)
minhp.add(1)
minhp.add(1)
minhp.printer()
print minhp.extractMin()
print minhp.extractMin()
def heapFullTest():
"""
Various tests for Heap class, using both MinHeaps and MaxHeaps, including sorting and random operations.
"""
print("Testing MinHeap: sorting")
for i in range(1, 21):
if heapRandomSort(250, True):
print "Test", i, "successful"
else:
print "Test", i, "failed"
print("\nTesting MaxHeap: sorting")
for i in range(1, 21):
if heapRandomSort(250, False):
print "Test", i, "successful"
else:
print "Test", i, "failed"
print("\nTesting MinHeap: general")
for i in range(1, 21):
if heapRandomTest(250, True):
print "Test", i, "successful"
else:
print "Test", i, "failed"
print("\nTesting MaxHeap: general")
for i in range(1, 21):
if heapRandomTest(250, False):
print "Test", i, "successful"
else:
print "Test", i, "failed"
print("\nTesting MinHeap: other operations")
ar = [1, 4, 501, -200, 32, 7, 65, -1, 20000, -34, 17]
min_heap = MinHeap()
min_heap.createMinHeap(ar)
print min_heap.extractMin()
print min_heap.extractMin()
print min_heap.extractMin()
max_heap = MaxHeap()
max_heap.createMaxHeap(ar)
print max_heap.extractMax()
print max_heap.extractMax()
print max_heap.extractMax()
print "Max: ar", max(
ar), "min_heap", min_heap.maximum(), "max_heap", max_heap.maximum()
print "Min: ar", min(
ar), "min_heap", min_heap.minimum(), "max_heap", max_heap.minimum()
class Calendar(object):
def __init__(self):
self.events = MinHeap()
self.mapper = {}
def add(self, record):
self.events.add(record.timestamp)
if record.timestamp in self.mapper:
self.mapper[record.timestamp].append(record)
else:
self.mapper[record.timestamp] = [record]
def getlatest(self):
rec_time = self.events.extractMin()
rec_list = self.mapper[rec_time]
# Logic here decides how to handle simultaneous events.
# Current Implementation - extract departure events first
record = None
index = -1
for idx in range(len(rec_list)):
if rec_list[idx].event_type == "E":
index = idx
break
if index < 0:
record = rec_list.pop(0)
else:
record = rec_list.pop(index)
if not len(rec_list):
del self.mapper[rec_time]
return record
def Dijkstra(self, v):
""" Runs Dijkstra shortest-path algorithm from source v, returning the list of distances from v, or None if any edges are negative-weight. """
if self.hasNegativeWeight():
return None # Dijkstra may not run properly if any weights are negative
# initialize the queue of vertices, the set s of "seen" or complete vertices, and the d list of current distances
q = MinHeap()
s = set()
d = [float("inf")] * self.vertexCount()
d[v] = 0
# insert source vertex in q; could insert all if using decreaseKey, but a basic Heap implementation doesn't support that
q.insert(KeyValuePair(d[v], v))
# loop through each edge vertex once, in order of distance from v, relaxing all edges out of that vertex
kvp = q.extractMin()
while kvp:
vert = kvp.value
dist = kvp.key
# only relax edges from a vertex if it has not already been visited
if vert not in s:
s.add(vert)
# relax edges to vertices not already completed
for e in self._adj[vert]:
if e.dest not in s:
if d[vert] + e.weight < d[e.dest]:
d[e.dest] = d[vert] + e.weight
q.insert(
KeyValuePair(d[e.dest], e.dest)
) # could also decrease key, but would not work with basic Heap implementation
# retrieve the next-lowest distance vertex
kvp = q.extractMin()
return d
