class LazyPrimMST:
def __init__(self, g):
self.pq = MinPQ()
self.marked = []
self.mst = Queue()
for i in range(g.v):
self.marked.append(False)
self.visit(g, 0)
while not self.pq.is_empty():
e = self.pq.del_min()
v = e.either()
w = e.other(v)
if self.marked[v] and self.marked[w]:
continue
self.mst.enqueue(e)
if not self.marked[v]:
self.visit(g, v)
if not self.marked[w]:
self.visit(g, w)
def visit(self, g, v):
self.marked[v] = True
for e in g.adj[v]:
if not self.marked[e.other(v)]:
self.pq.insert(e)
class BellmanFordSP:
def __init__(self, g, s):
self.dist_to = []
self.edge_to = []
self.on_q = []
self.queue = Queue()
self.cost = 0
for i in range(g.v):
self.dist_to.append(float('inf'))
self.edge_to.append(None)
self.on_q.append(None)
self.queue.enqueue(s)
self.on_q[s] = True
while not self.queue.is_empty() and not self.has_nagative_cycle():
v = self.queue.dequeue()
self.on_q[v] = False
self.relax(g, v)
def relax(self, g, v):
for e in g.adj[v]:
w = e.v_to
if self.dist_to[w] > self.dist_to[v] + e.weight:
self.dist_to[w] = self.dist_to[v] + e.weight
self.edge_to[w] = e
if not self.on_q[w]:
self.on_q[w] = True
self.queue.enqueue(w)
def bfs(self, g, s):
q = Queue()
q.enqueue(s)
self.marked[s] = True
while not q.is_empty():
v = q.dequeue()
for w in g.get_adj(v):
if not self.marked[w]:
self.edge_to[w] = v
self.marked[w] = True
q.enqueue(w)
class KruskalMST:
def __init__(self, g):
self.mst = Queue()
self.pq = MinPQ()
self.uf = UF(g.v)
for e in g.edges:
self.pq.insert(e)
while not self.pq.is_empty() and self.mst.size() < g.v - 1:
e = self.pq.del_min()
v = e.either()
w = e.other(v)
if self.uf.connected(v, w):
continue
self.mst.enqueue(e)
self.uf.union(v, w)
class DepthFirstOrder:
def __init__(self, g):
self.marked = []
self.pre = Queue()
self.post = Queue()
self.reverse_post = Stack()
for i in range(g.get_v()):
self.marked.append(False)
for v in range(g.get_v()):
if not self.marked[v]:
self.dfs(g, v)
def dfs(self, g, v):
self.marked[v] = True
self.pre.enqueue(v)
for w in g.get_adj(v):
if not self.marked[w]:
self.dfs(g, w)
self.post.enqueue(v)
self.reverse_post.push(v)
class DigraphOrder:
def __init__(self, g):
self.pre = Queue()
self.post = Queue()
self.reverse_post = Stack()
self.marked = []
for i in range(g.v):
self.marked.append(False)
for v in range(g.v):
if not self.marked[v]:
self.dfs(g, v)
def dfs(self, g, v):
self.marked[v] = True
self.pre.enqueue(v)
for e in g.adj[v]:
w = e.v_to()
if not self.marked[w]:
self.dfs(g, w)
self.post.enqueue(v)
self.reverse_post.push(v)