Hydrate the nodes

Problem Statement

Hydrate the nodes Problem Description There is a tree with n nodes. The tree is rooted at node with number 0. As usually in computer science, the tree grows upside down comparing to trees existing in nature. Apples grow on nodes of this tree. Some of these apples are underhydrated, some are overhydrated, and others are neither. You know that for each overhydrated apple you'll get overhydratedPenalty cents and for every underhydrated you'll get underhydratedPenalty cents. Now, you want to pour water on exactly one node of the tree. When you pour water on node v , all apples that are in v 's subtree, i.e. v itself and all descendants of v , will be hydrated and in consequence each hydrated apple that was almost overhydrated becomes overhydrated. Moreover, every apple in the whole tree that was almost underhydrated and no water was poured on it gets underhydrated. Calculate the minimum total penalty you can get from pouring water on exactly one node of the tree. Complete the function mini