We were waiting several weeks tp setting this contest and hope the problem was good enough.
I will write the full editorial in the few next days, now some hints and short solutions exist here.
805C - Find Amir / 804A - Find Amir
805D - Minimum number of steps / 804B - Minimum number of steps
805E - Ice cream coloring / 804C - Ice cream coloring
There were some opinion about this sentence of the problem:
Vertices which have the i-th (1 ≤ i ≤ m) type of ice cream form a connected subgraph.
A subgraph S of a graph G is a graph whose set of vertices and set of edges are all subsets of G. And according to this definition, the subgraph can also be empty as a subset of vertices and edges.
A graph which is connected in the sense of a topological space, i.e., there is a path from any point to any other point in the graph. A graph that is not connected is said to be disconnected. This definition means that the null graph and singleton graph are considered connected, while empty graphs on 2 ≤ n nodes are disconnected.
All of these definitions were from valid articles and it seems more logical. How ever, I should apologize all of the participants because of bad sample tests when some of articles and books didn't accept my opinion.
805F - Expected diameter of a tree / 804D - Expected diameter of a tree
solution and try to improve it.
