##### ###### ##### ### # # ### # # ###### ## ## ## ## ## ## ## # # # # # ## ##### #### ##### # # # # # # # #### ## # ## ## ## ## # # # # # ## ## # ###### ## ### # ### # ######
##### ###### ##### ### # # ### # # ###### ## ## ## ## ## ## ## # # # # # ## ##### #### ##### # # # # # # # #### ## # ## ## ## ## # # # # # ## ## # ###### ## ### # ### # ######
Tree = connected + acyclic
Given nodes and a list of undirected edges, check if these edges form a valid tree. A valid tree must be:
Connected (one component)
Acyclic (exactly edges) Example: , edges is a tree. , edges is not (has a cycle). Constraints: from to , edges from to .
