摘要：
1821 最优集合 1821 最优集合 1821 最优集合 一个集合S的优美值定义为：最大的x，满足对于任意i∈[1,x]，都存在一个S的子集S'，使得S'中元素之和为i。 给定n个集合，对于每一次询问，指定一个集合S1和一个集合S2，以及一个数k，要求选择一个S2的子集S3(|S3|<=k)，使得 阅读全文
摘要：
F. PolandBall and Gifts It's Christmas time! PolandBall and his friends will be giving themselves gifts. There are n Balls overall. Each Ball has some 阅读全文
摘要：
题目链接：http://codeforces.com/contest/762/problem/D 多多分析状态；这个很明了 阅读全文
摘要：
C. Mahmoud and a Message Mahmoud wrote a message s of length n. He wants to send it as a birthday present to his friend Moaz who likes strings. He wro 阅读全文
摘要：
E. Game of Stones Sam has been teaching Jon the Game of Stones to sharpen his mind and help him devise a strategy to fight the white walkers. The rule 阅读全文
摘要：
DNA repair Problem Description Biologists finally invent techniques of repairing DNA that contains segments causing kinds of inherited diseases. For t 阅读全文
摘要：
D. Bear and Tree Jumps A tree is an undirected connected graph without cycles. The distance between two vertices is the number of edges in a simple pa 阅读全文
摘要：
题目链接：http://codeforces.com/contest/440/problem/D D. Berland Federalization D. Berland Federalization Recently, Berland faces federalization requests m 阅读全文
摘要：
题目链接：http://codeforces.com/contest/709/problem/E 题意： 给你一棵树，你可以任删一条边和加一条边，只要使得其仍然是一棵树，输出每个点是否都能成为重心 题解： 做题多动手，画一画； 假设要求当前节点i是否能经过操作成为重心，将它提起来为根，那么可以知道， 阅读全文
摘要：
C3. Brain Network (hard) Breaking news from zombie neurology! It turns out that – contrary to previous beliefs – every zombie is born with a single br 阅读全文