最大流问题python代码
时间: 2023-10-17 16:22:27 浏览: 50
下面是使用Ford-Fulkerson算法求解最大流的Python代码:
```python
from collections import defaultdict
class Graph:
def __init__(self, graph):
self.graph = graph
self. ROW = len(graph)
def BFS(self, s, t, parent):
visited = [False] * (self.ROW)
queue = []
queue.append(s)
visited[s] = True
while queue:
u = queue.pop(0)
for ind, val in enumerate(self.graph[u]):
if visited[ind] == False and val > 0 :
queue.append(ind)
visited[ind] = True
parent[ind] = u
return True if visited[t] else False
def FordFulkerson(self, source, sink):
parent = [-1] * (self.ROW)
max_flow = 0
while self.BFS(source, sink, parent) :
path_flow = float("Inf")
s = sink
while(s != source):
path_flow = min(path_flow, self.graph[parent[s]][s])
s = parent[s]
max_flow += path_flow
v = sink
while(v != source):
u = parent[v]
self.graph[u][v] -= path_flow
self.graph[v][u] += path_flow
v = parent[v]
return max_flow
# 使用示例
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]]
g = Graph(graph)
source = 0; sink = 5
print("最大流为:%d " % g.FordFulkerson(source,sink))
```
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