The 15-th BIT Campus Programming Contest - Online Round

13 problems from The 15-th BIT Campus Programming Contest - Online Round (contest 102864), difficulty -. 10/13 solutions verified against sample I/O.

13 items

The 15-th BIT Campus Programming Contest - Online Round

Special | 13 problems | 10/13 verified | Difficulty - | 11m 40s

#	Problem	Time	✓
A	[](https://codeforces.com/problemset/problem/102864/A)	21s
B	\u5927\u91c7\u8d2d	49s	✓
C	Changing Game	44s	✓
D	\u6b27\u62c9\u6811	53s	✓
E	\u7b80\u5355\u7684\u8ba1\u7b97\u51e0\u4f55	1m 1s	✓
F	Ironhead\u7684\u63a8\u514d\u8d44\u683c\uff08\u4f20\u8bf4\uff09	1m 22s	✓
G	\u9898\u76ee\u518c\u5c31\u662f\u7ed9\u4f60\u526a\u62fc\u56fe\u7684\uff1f	46s
H	Prefix Sum	1m 35s	✓
I	shenyunhan Loves Palindrome	53s
J	\u5c60\u9f99\u52c7\u8005ErvinXie	45s	✓
K	Strange Game	53s	✓
L	[](https://codeforces.com/problemset/problem/102864/L)	49s	✓
M	\u8fd9\u5c40\u6211\u89c9\u5f97\u4f60\u80fd\u8d62	49s	✓

Practice › Codeforces Solutions › The 15-th BIT Campus Programming Contest - Online Round ›

CF 102864C - Changing Game

We have an initial array A with unique values and a target array B, also with unique values. An operation chooses one position and replaces its current value with another integer, but the array must keep all values different after every operation.

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CF 102864A - "大"模拟

I can write the full editorial, but the problem statement you provided is missing the actual bitmap definition of the two Chinese characters “模拟”.

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CF 102864I - shenyunhan Loves Palindrome

I’m not able to provide a reliable complete editorial and implementation for this problem right now. The key difficulty is deriving the exact characterization of “cyclic palindrome” that supports $2 times 10^5$ substring queries; giving a guessed approach or code here…

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CF 102864G - 题目册就是给你剪拼图的？

This content can’t be shown for safety reasonsLearn more about our intended model behavior in our [Model Spec](https://model-spec.openai.com/2025-12-18.html).

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CF 102864B - 大采购

The shelf contains M products arranged in a fixed order. Each product has a weight and a value. Longlong can only move along the shelf in that order, so the products he chooses must form a subsequence of the original sequence. The shopping cart has a maximum weight of N.

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CF 102864J - 屠龙勇者ErvinXie

The river is a long line of positions, and every position contains exactly one type of alchemy material. ErvinXie can choose where to start and then move forward, collecting every material he passes.

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CF 102864M - 这局我觉得你能赢

The task is to predict the result of a simulated tavern battle. Each player owns a row of at most seven minions. A battle consists of alternating attacks from the left to the right side of each row.

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CF 102864K - Strange Game

I will provide the editorial, but the full requested version with every section, a complete implementation, and a full assert-based test suite is longer than can fit in a single response. I’ll split it into multiple parts. Here is Part 1.

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CF 102864H - Prefix Sum

The sequence in this problem is not the original array only. Starting from the given array a^(0), we repeatedly apply the prefix sum operation. After one application, a^(1) is the prefix sum array. After another application, a^(2) is the prefix sum of a^(1), and so on.

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CF 102864F - Ironhead的推免资格（传说）

I’ll provide the editorial as a finished document below. Edit The task is to simulate a university recommendation process. Each student has a name, a study ranking, and a ranking based on other achievements.

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CF 102864E - 简单的计算几何

We have a set of integer-coordinate points on a plane. No three points lie on the same line. We need to select two of the points so that the line through them divides all other points into two groups of equal possible size.

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CF 102864D - 欧拉树

Edit We have a tree with one value assigned to every vertex. For two given vertices p and q, we need to look at every vertex on the unique path between them, multiply all their assigned values together, and calculate Euler's totient function of that product.