写一个网络最大流算法并标上注释
时间: 2024-03-26 11:35:00 浏览: 14
好的,以下是一个基于Ford-Fulkerson算法的网络最大流算法,并标有注释。
```python
from collections import defaultdict
# 用于存储图的类
class Graph:
def __init__(self, vertices):
self.graph = defaultdict(dict) # 存储有向图的字典
self.V = vertices # 图的顶点数
# 添加边到图
def add_edge(self, u, v, w):
self.graph[u][v] = w
# 从顶点s到t的最大流
def max_flow(self, s, t):
# 初始化残留图
residual_graph = [self.graph[i].copy() for i in range(self.V)]
# 初始化最大流为0
max_flow = 0
# 循环直到无法找到增广路径
while True:
# 存储路径上每个节点的前驱以及该节点到源点的最小剩余容量
parent = [-1] * self.V
parent[s] = -2
min_capacity = [0] * self.V
min_capacity[s] = float('inf')
# BFS搜索增广路径
queue = [s]
while queue:
u = queue.pop(0)
for v in residual_graph[u]:
if parent[v] == -1 and residual_graph[u][v] > 0:
parent[v] = u
min_capacity[v] = min(min_capacity[u], residual_graph[u][v])
if v == t:
break
queue.append(v)
# 如果没有找到增广路径,则算法结束
if parent[t] == -1:
break
# 更新最大流
max_flow += min_capacity[t]
# 更新残留图
v = t
while v != s:
u = parent[v]
residual_graph[u][v] -= min_capacity[t]
residual_graph[v][u] += min_capacity[t]
v = u
return max_flow
```
注释中会解释算法的每个步骤,但如果你对网络流算法不熟悉,建议你先学习相关知识再来理解这个算法。