adjacency-list

If each node maps to a set of the nodes it has edges to, instead of a list, we would gain the ability to gain constant time lookup of edges, instead of having to traverse the whole list. The only disadvantage I can think of is slightly more memory overhead and time to enumerate the edges of a node, but not asymptotically significantly so. I think "list" is just a generic label, not to be taken literally. I've used a Set and it works perfectly well. If I recall correctly, my textbook also used a Set . 来源： https://stackoverflow.com/questions/32588468/why-are-graphs-represented-using-an-adjacency

I'm trying to find similar adjacent items in List and count its number, e.g.: List<string> list = new List<string> {"a", "a", "b", "d", "c", "c"}; Desired Output: a = 2, c = 2 What I've done is use for loop to iterate over each element of the list and to see whether it has similar adjacent element, but understandably it gives ArgumentOutOfRangeException() because I don't know how to keep track of the position of the iterator so that it doesn't go out of bounds. Here's what I've done: for (int j = 0; j < list.Count; j++) { if (list[j] == "b") { if ((list[j + 1] == "b") && (list[j - 1] == "b"))

I have a table in my database where I store a tree structure using the hybrid Nested Set (MPTT) model (the one which has lft and rght values) and the Adjacency List model (storing parent_id on each node). my_table (id, parent_id, lft, rght, alias) This question doesn't relate to any of the MPTT aspects of the tree but I thought I'd leave it in in case anyone had a good idea about how to leverage that. I want to convert a path of aliases to a specific node. For example: "users.admins.nickf" would find the node with alias "nickf" which is a child of one with alias "admins" which is a child of