21st UESTC Programming Contest - Preliminary

18 problems from 21st UESTC Programming Contest - Preliminary (contest 104279), difficulty -. 16/18 solutions verified against sample I/O.

18 items

21st UESTC Programming Contest - Preliminary

Special | 18 problems | 16/18 verified | Difficulty - | 19m 12s

#	Problem	Time	✓
A	\u80fd\u91cf\u91c7\u96c6	1m 8s	✓
B	A Boring Game	59s	✓
C	\u5f80\u65e5\u91cd\u73b0	1m 3s	✓
D	\u5c0f\u7f8e\u7231\u753b\u9c7c	1m 5s	✓
E	\u5c0f\u56e2\u6765\u6253\u5b57	55s	✓
F	\u70b8\u5f39\u9e2d	2m 7s
G	Guard the Kingdom	50s	✓
H	\u7ea6\u745f\u592b\u95ee\u9898	51s	✓
I	\u516c\u4e3b\u8fde\u7ed3\uff01Re:Dive	50s	✓
J	\u6570\u77e9\u5f62	47s	✓
K	\u6253\u5730\u9f20	1m 2s	✓
L	\u6811\u8fb9\u91cd\u6392	48s	✓
M	\u64cd\u4f5c\u7cfb\u7edf\u8ba1\u7b97\u9898	1m 6s	✓
N	\u672c\u8d28\u4e0d\u540c\u7684 01 \u73af\u8ba1\u6570	50s	✓
O	\u722c\u5854	2m 9s
P	\u4e09\u7ef4\u6a21\u578b	52s	✓
Q	Du Cuo Ti Le	55s	✓
R	postcard	55s	✓

Practice › Codeforces Solutions › 21st UESTC Programming Contest - Preliminary ›

CF 104279O - 爬塔

Let $S={1,dots,m}$ denote the selector variables and $T={m+1,dots,m+2^m}$ the data variables of the multiplexer $Mm$. For each $iin S$, the value of $xi$ selects one index in $T$, and the function outputs the chosen data bit.

Practice › Codeforces Solutions › 21st UESTC Programming Contest - Preliminary ›

CF 104279R - postcard

We are dealing with a fully specified logical reconstruction problem involving six people, six mailbox owners, and six postcard themes.

Practice › Codeforces Solutions › 21st UESTC Programming Contest - Preliminary ›

CF 104279Q - Du Cuo Ti Le

We are given an array of length $2n$, initially all zeros. We also receive $n$ interval assignment operations. Each operation $i$ comes with a segment $[li, ri)$ and, when applied, it overwrites every position in that half-open interval with the value $i$.

Practice › Codeforces Solutions › 21st UESTC Programming Contest - Preliminary ›

CF 104279P - 三维模型

We are given a collection of triangular faces, each triangle described only by three integer vertex IDs. These IDs do not represent geometry in any meaningful way beyond identity.

Practice › Codeforces Solutions › 21st UESTC Programming Contest - Preliminary ›

CF 104279N - 本质不同的 01 环计数

We are working with binary strings arranged on a circle. Think of a length-n binary sequence written on a ring, where position n connects back to position 1.

Practice › Codeforces Solutions › 21st UESTC Programming Contest - Preliminary ›

CF 104279M - 操作系统计算题

We are given a collection of processes. Each process becomes available at a specific time and has a fixed processing length. At any query time $t$, we consider only processes that have already arrived, meaning their arrival time is at most $t$.

Practice › Codeforces Solutions › 21st UESTC Programming Contest - Preliminary ›

CF 104279K - 打地鼠

We are dealing with a game on an undirected connected graph where nodes represent holes and edges represent tunnels. A mouse starts at some unknown node. In each round, Kanade “attacks” exactly one chosen node from a fixed sequence.

Practice › Codeforces Solutions › 21st UESTC Programming Contest - Preliminary ›

CF 104279L - 树边重排

We are given a tree with n vertices and n − 1 undirected edges. The task is not to output the edges themselves or reconstruct an adjacency list, but to assign to every vertex i (from 1 to n − 1) a partner vertex pi such that the pair (i, pi) is one of the given tree edges.

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CF 104279F - 炸弹鸭

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CF 104279J - 数矩形

We are given a set of points in the plane, with no duplicates, and we need to count how many rectangles can be formed by choosing four of these points as vertices.

Practice › Codeforces Solutions › 21st UESTC Programming Contest - Preliminary ›

CF 104279I - 公主连结！Re:Dive

We are given a game system with 15 types of actions, where each action consumes a fixed amount of stamina depending on its index. Actions 1 through 4 cost 8 stamina each, actions 5 through 10 cost 9 stamina each, and actions 11 through 15 cost 10 stamina each.

Practice › Codeforces Solutions › 21st UESTC Programming Contest - Preliminary ›

CF 104279H - 约瑟夫问题

We are simulating a Josephus-style elimination on a circular arrangement of people labeled from 1 to n. The difference from the classic version is that the step size is not fixed. Instead, there are q rounds, and each round provides its own step value k.

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CF 104279G - Guard the Kingdom

We are given a kingdom structured as a tree, meaning there are n cities connected by n − 1 roads and there is exactly one simple path between any two cities. Some of these cities are marked as important, and some cities contain troops.

Practice › Codeforces Solutions › 21st UESTC Programming Contest - Preliminary ›

CF 104279D - 小美爱画鱼

We are given several independent test cases. In each test case, we are working on a grid in the first quadrant. Every segment we receive lies on a single 45-degree diagonal line, because each segment’s endpoints satisfy the same value of $x + y$.

Practice › Codeforces Solutions › 21st UESTC Programming Contest - Preliminary ›

CF 104279E - 小团来打字

We are given a sequence of typing requests. Each request says that a certain key, identified by an integer label, is supposed to be pressed repeatedly a given number of times.

Practice › Codeforces Solutions › 21st UESTC Programming Contest - Preliminary ›

CF 104279A - 能量采集

We are given a grid with $n$ rows and $m$ columns. Each cell contains one character, either $A$ or $B$. Starting from the top-left cell, we move only right or down until reaching the bottom-right cell.

Practice › Codeforces Solutions › 21st UESTC Programming Contest - Preliminary ›

CF 104279C - 往日重现

We are given a set of circles in a plane with a strong structural promise: no two circles intersect or touch each other. This restriction forces a very rigid geometry. Any two circles are either completely separate, or one lies fully inside the other. There is no partial overlap.

Practice › Codeforces Solutions › 21st UESTC Programming Contest - Preliminary ›

CF 104279B - A Boring Game

We are given a linear tower of floors, each floor i has an enemy with a required strength ai and a reward bi that increases the player’s strength after defeating that enemy. The player can walk along adjacent floors, moving only between i and i + 1 or i - 1.