从邻接列表图中删除边

Question

我正在玩this code，其中不包含remove_edge方法。

我的尝试如下：

def remove_edge(self, src, dest):
    new_graph = []
    for i in range(self.V):
        node = self.graph[i]
        while node is not None:
            if i == src and node.vertex == dest:
                new_graph.append(AdjNode(src))
            elif i == dest and node.vertex == src:
                new_graph.append(AdjNode(dest))
            else:
                new_graph.append(node)
            node = node.next
    self.graph = new_graph

...但是稍后稍后调用has_edge时，它将导致索引错误。我假设添加一个没有next值的新节点在这里可以工作，但是我需要做一些不同的事情。

这是完整的代码：

class AdjNode:
    def __init__(self, data):
        self.vertex = data  # int
        self.next = None  # behave like a linked list node


class AdjGraph:
    def __init__(self, num_vertices):
        self.V = num_vertices
        self.graph = [None] * self.V

    # Function to print the graph
    def print_graph(self):
        for i in range(self.V):
            print("Adjacency list of vertex {}\n head".format(i), end="")
            temp = self.graph[i]
            while temp:
                print(" -> {}".format(temp.vertex), end="")
                temp = temp.next
            print(" \n")

    def add_edge(self, src, dest):
        # undirected...
        node = AdjNode(dest)
        node.next = self.graph[src]
        self.graph[src] = node

        node = AdjNode(src)
        node.next = self.graph[dest]
        self.graph[dest] = node

    def has_edge(self, src, dest):
        for i in range(self.V):
            node = self.graph[i]
            while node is not None:
                if i == src and node.vertex == dest:
                    return True
                if i == dest and node.vertex == src:
                    return True
                node = node.next
        return False


# tests:
graph = AdjGraph(5)
graph.add_edge(0, 1)
graph.add_edge(3, 1)

print(graph.has_edge(1, 3))  # True, as expected
graph.remove_edge(1, 3)
print(graph.has_edge(1, 3)) # expecting False here but I get an error:


  File "~\Desktop\pytester.py", line 96, in <module>
    print(graph.has_edge(1, 3))
  File "~\Desktop\pytester.py", line 64, in has_edge
    node = self.graph[i]
IndexError: list index out of range