Codeforces Round #453

Visiting a Friend

Solution

Coloring a Tree

自顶向下

Hashing Trees

连续2层节点数都超过1时能异构

GCD of Polynomials

斐波那契数列为什么那么重要，所有关于数学的书几乎都会提到？ - 王希的回答 - 知乎 https://www.zhihu.com/question/28062458/answer/39763094

Bipartite Segments

Weighting a Tree

Cyclic Cipher