Update graph_adjacency_matrix.py

[Fuuuuuji]

理解K神这个实现主要是为了演示邻接矩阵的基本原理，但在实际使用中可能会遇到一些限制：在实际应用中，通常使用顶点的值而不是索引来操作图。所以，为了更“公平”地与邻接表方法的对比，进行了改进：

1. 引入 vertex_map：使用字典 vertex_map 来存储顶点值到索引的映射。
2. 基于值的操作：add_vertex, remove_vertex, add_edge, 和 remove_edge 方法现在都使用顶点值而不是索引。这使得图的操作更加直观和用户友好。
3. 动态索引管理：在 remove_vertex 方法中，更新了剩余顶点的索引映射。这确保了在删除顶点后，其他顶点的索引仍然保持正确。

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[krahets]

在实际应用中，通常使用顶点的值而不是索引来操作图

这样无法处理有节点值重复的情况，我倾向于保留当前实现