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题&解
  • Crimson boi can u water it [13] 几把水题
    题&解

    Crimson boi can u water it [13] 几把水题

    题目背景 南大几把选拔中最水的题(T3), 适合出在初中竞赛里. 另外这期写解答方便以后想考南大几把的学生😇, 篇幅太长除了题面不写中文了. 不过题面也是pmt提供的, 不一定完全准确. 题面 记排列P的置换环数量为c(P),排列P,Q的复合记为P\oplus Q,已知长度为n的排列f_1,f……
    HDD 2023年9月6日
  • Orange Boy Can You Solve It Out? Ep. 55
    OBCYSIO

    Orange Boy Can You Solve It Out? Ep. 55

    思考题 with hard-to-write checker and interactor Peripheral Lightup! Note: this is not a traditional problem. Follow the instruction in the statement to help construct your solution Lead-in: The Palace is celebrating a festival with LED lights! Ins……
    XGN 2023年7月20日
  • 英語読解問題(嘘)
    题&解

    英語読解問題(嘘)

    XGN 2023年6月4日
  • Orange Boy Can You Solve It Out? Ep. 54
    OBCYSIO

    Orange Boy Can You Solve It Out? Ep. 54

    思考题 in dreamland Construct it XGN dreamt about the following problem when sleeping: You are given a positive integer n (2\leq n\leq 10^8). Output an arithmetic expression that yields the value n with the following requirements: The expression s……
    XGN 2023年6月3日
  • Crimson-boi[12] 脑筋急转弯
    题&解

    Crimson-boi[12] 脑筋急转弯

    题目背景 贴吧范畴论帅哥问的一道题, 题目还算基础, 不过确实很容易伪证, 是名副其实的脑筋急转弯. 题面 对一个拓扑空间X, 定义集合S为稠密集当且仅当\text{Cl}(S)=X, R为无处稠密集当且仅当X-\text{Cl}(R)为稠密集. 定义集合A的边界\text{Bd}(A)=\text{Cl}(A)\cap\te……
    HDD 2023年5月27日
  • Crimson-boi[11] 创新高考题
    题&解

    Crimson-boi[11] 创新高考题

    题目背景 总有人喜欢在高考数学中嚷嚷"仿射变换", 于是一道纯正射影几何高考"创新题"应运而生(其实还顺便测试一下QuickLaTex). 题面 如上图, , , 共线, , , 共线, , , 共线, 且, , 不共线, , , 不共线. (1) 若与不是同一平面, 求证与的交点, 与的交点, 与的交点共线.……
    HDD 2023年4月23日
  • Orange Boy Can You Solve It Out? Ep. 53 - Gaokao Special 2
    OBCYSIO

    Orange Boy Can You Solve It Out? Ep. 53 - Gaokao Special 2

    思考题 which is an adaptation from a popular problem. The source problem is very popular. IDK if this adaptation has been made or not. Adaptation There are N people indexed from 1 to N in a room. Each of them is given a hat of a random color. The t……
    XGN 2023年3月15日
  • Orange Boy Can You Solve It Out? Ep. 52 - Gaokao Special 1
    OBCYSIO

    Orange Boy Can You Solve It Out? Ep. 52 - Gaokao Special 1

    Finally some geometry! Maybe very easy though. Currently I am undergoing the College Entrance Exam(GK) so I don't have many ideas for Competitive Programming problems. This problem is inspired by some math problem in GK Simulation. Of course, this ……
    XGN 2023年3月15日
  • Orange Boy Can You Solve It Out? Ep. 51
    OBCYSIO

    Orange Boy Can You Solve It Out? Ep. 51

    思考题 of Div2B-C Elevator Welcome back to OBCYSIO! Orange Boy has been promoted to LGM boy so this series is in an awkward situation. This problem is very easy. Consider an elevator with a max speed of v_m m/s and an acceleration of a m/s^2. When ……
    XGN 2022年10月30日
  • Crimson-boi[10] 我是大专生 ;( ;( ;(
    题&解

    Crimson-boi[10] 我是大专生 ;( ;( ;(

    题目背景 庆祝Crimson Boy提前一步进入大学殿堂, 特此准备一道来自他所在的大学的隔壁敌对大学的微积分题目! 题面 \forall x\in[1,+\infty), f(x)>0, f''(x)\leq0且\lim\limits_{x\rightarrow+\infty}f(x)=+\infty. 计算\lim\limits_{s\rightarrow0^+}\sum\limits_{n=……
    HDD 2022年9月6日