Python Bellman-Ford算法：我无法正确实现Relax函数

问题描述

我正在实现Bellman-Ford算法。我正在测试的图形在CLRS中：Graph。
这是我的图形初始化：

def connect_nodes_directed(graph,source,destination,weights=1):
    graph[source].append((destination,weights))

num_nodes = 5
graph = [[] for _ in range(num_nodes)]
connect_nodes_directed(graph,1,6)
connect_nodes_directed(graph,2,7)
connect_nodes_directed(graph,8)
connect_nodes_directed(graph,4,9)
connect_nodes_directed(graph,3,-3)
connect_nodes_directed(graph,2)
connect_nodes_directed(graph,-4)
connect_nodes_directed(graph,5)
connect_nodes_directed(graph,-2)
connect_nodes_directed(graph,7)
for i in graph:
    print(i)

注意：s,t,y,x,z分别是0,4。
结果：

[(1,6),(2,7)]
[(2,8),(4,-4),(3,5)]
[(4,9),-3)]
[(1,-2)]
[(0,2),7)]

这是我正在实现的代码，仅适用于relax函数：

def init_single_source(graph,source):
    distance_to = [float("inf")] * len(graph)
    distance_to[source] = 0
    return distance_to

def relax(source,weights,distance_to,parents):
    if distance_to[destination] > distance_to[source] + weights:
        distance_to[destination] = distance_to[source] + weights
        parents[destination] = source

def bellman_ford_sssp(graph,source):
    parents = [None] * len(graph)
    distance_to = init_single_source(graph,source)
    for i in range(len(graph)):
        for j in graph[i]:
            relax(i,j[0],j[1],parents) # j[0] is destination,j[1] is weights
    print(distance_to)

输入为(graph,0)，结果为：[0,7,2]，应改为[0,-2]。我无法弄清楚我做错了什么。谁能发现它？非常感谢。

解决方法

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