摘要：Two-Letter Card Game You are given a deck of cards represented by a string array cards, and each card displays two lowercase letters. You are also giv 阅读全文

摘要：F. Rada and the Chamomile Valley Yesterday, Rada found a portal that can transport her to the Chamomile Valley and back. Rada's happiness knew no boun 阅读全文

摘要：Re:从零开始的近世代数复习（hard） 题目描述 期末考还有最后一门考试--近世代数，但是小明还在进行出题，他必须从零开始复习近世代数。近世代数是一门非常复杂的课，挂科率很高，小明决定找到最优的复习策略。 假设近世代数中有 $n$ 个不同的定理 $1$ 到 $n$，每个定理有不同的难度，导致每个定 阅读全文

摘要：F. Unjust Binary Life Yuri is given two binary strings $a$ and $b$, both of which are of length $n$. The two strings dynamically define an $n \times n 阅读全文

摘要：E. Ancient Tree Bahamin came from the past to visit Ali — who came from the future. He also brought an ancient tree as a gift for Ali. He noticed some 阅读全文

摘要：[CTSC1997] 选课 题目描述 在大学里每个学生，为了达到一定的学分，必须从很多课程里选择一些课程来学习，在课程里有些课程必须在某些课程之前学习，如高等数学总是在其它课程之前学习。现在有 $N$ 门功课，每门课有若干学分，分别记作 $s_1,s_2,\cdots,s_N$，每门课有一门或没有直 阅读全文