13.System entities and interfaces 系统实体和接口 See also Clause 4 for a discussion on general concepts and Clause 5 for generic entity model. 参见条目 4 讨论总体概念、条目 5 通用实体模型。 An entity specification should specify the embodied functions and …
E. Iris and the Tree
#树形结构 #贪心 #数学
题目描述
Given a rooted tree with the root at vertex 1 1 1. For any vertex i i i ( 1 ≤ i ≤ n 1 \leq i \leq n 1≤i≤n) in the tree, there is an edge connecting vertices i i i and p i p_i pi ( 1 ≤ p i ≤…