A 签到题 注意字符必须改变，有(ab, xy)肯定是不行的 B 填数+规律 题意 在$n\times n$的网格中填数，先1~ceil(n*n/2)顺序填
A 通配符匹配 问可带有通配符$*$的$s$串能否匹配上$t$串 code 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 #include <bits/stdc++.h>using namespace

# Introduction

cf 502场 C的一道构造题背后的离散数学原理：Dilworth定理

shell脚本 1 2 3 4 5 6 7 python3 -c " import requests; from bs4 import BeautifulSoup; url = input('请输入题目网址'); return_data = requests.get(url, verify=True); soup = BeautifulSoup(str(return_data.text), 'html.parser'); print(str(soup.find_all('div', 'ttypography')[0]).replace('src=\"', 'src=\"https://codeforces.com').replace(r'$', r'$'))"
Description A knight jumps around an infinite chessboard. The chessboard is an unexplored territory. In the spirit of explorers, whoever stands on a square for the first time claims the ownership of this square. The knight initially owns the square he stands, and jumps $N$ times before he gets bored. Recall that a knight can jump in 8 directions. Each direction consists of two squares forward and then one squaure