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Python:实现ford fulkerson网络流算法(附完整源码)


Python:实现ford fulkerson网络流算法

def BFS(graph, s, t, parent):
# Return True if there is node that has not iterated.
visited = [False] * len(graph)
queue = []
queue.append(s)
visited[s] = True

while queue:
u = queue.pop(0)
for ind in range(len(graph[u])):
if visited[ind] is False and graph[u][ind] > 0:
queue.append(ind)
visited[ind] = True
parent[ind] = u

return True if visited[t] else False


def FordFulkerson(graph, source, sink):
# This array is filled by BFS and to store path
parent = [-1] * (len(graph))
max_flow = 0
while BFS(graph, source, sink, parent):
path_flow = float("Inf")
s = sink

while s != source:
# Find the minimum value in select path
path_flow = min(path_flow, graph[parent[s]][s])
s = parent[s]

max_flow += path_flow
v = sink

while v != source:
u = parent[v]
graph[u][v] -= path_flow
graph[v][u] += path_flow
v = parent[v]
return max_flow


graph = [
[0, 16, 13, 0, 0, 0],
[0, 0, 10, 12, 0, 0],
[0, 4, 0, 0, 14, 0],
[0, 0, 9, 0, 0, 20],
[0, 0, 0, 7, 0, 4],
[0, 0, 0, 0, 0, 0],
]

source, sink = 0, 5
print(FordFulkerson(graph, source, sink))


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