The 21st Sichuan University Programming Contest

15 problems from The 21st Sichuan University Programming Contest (contest 104377), difficulty -. 15/15 solutions verified against sample I/O.

15 items

The 21st Sichuan University Programming Contest

Special | 15 problems | 15/15 verified | Difficulty - | 15m 15s

# Problem Rating Tags Accepted Time ✓
A \u8ba1\u7b97\u5f02\u6216\u548c 1m 27s ✓
B \u6700\u5927\u4ef7\u503c 56s ✓
C \u4e8c\u7ef4\u6570\u7ec4\u53d8\u6362 1m 10s ✓
D \u968f\u673a\u6570\u751f\u6210\u5668 1m 8s ✓
E \u4f20\u611f\u5668\u5bf9\u9f50 1m 13s ✓
F \u73c2\u6735\u8389\u6811 59s ✓
G \u6211\u7684\u8f66\u5462\uff1f 55s ✓
H \u8d26\u53f7\u5df2\u6ce8\u9500\uff0c\u6211\u60f3\u8d26\u53f7\u5df2\u6ce8\u9500\u4e86 58s ✓
I \u8fd9\u771f\u7684\u662f\u7b7e\u5230\u9898 52s ✓
J BLG\u51b2\u51b2\u51b2\uff01 59s ✓
K \u5b57\u7b26\u4e32\u6e38\u620f 54s ✓
L MEX\u95ee\u9898 54s ✓
M \u6570\u5b57\u6a21\u62df 47s ✓
N \u89e3\u5bc6 1m 2s ✓
O \u6355\u9c7c\u8fbe\u4eba\uff01 1m 1s ✓
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CF 104377O - 捕鱼达人！

We are given a set of points in the plane, each point carrying a positive or negative value. A fisherman stands at the origin and can deploy a net in a very flexible way.
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CF 104377N - 解密

We are given a sequence of 2×2 matrices that play the role of convolution kernels, and another implicit sequence of 2×2 matrices that acts as the inverse under the same convolution rule. More concretely, each input test case gives a list of matrices $A0, A1, dots, A{n-1}$.
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CF 104377M - 数字模拟

We are given a fixed-height ASCII picture consisting of 5 rows and 18 columns. Each column contains either a star character or a dot-like blank representation, and together these characters encode three digits written side by side.
codeforces competitive-programming Jul 1, 2026
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CF 104377L - MEX问题

We are given a sequence of integers, and we are asked to count how many of its subsequences satisfy a structural constraint that depends on the MEX of every prefix of that subsequence.
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CF 104377K - 字符串游戏

We are given two players, each owning a collection of string “tiles”. The first player has $n$ distinct tile types, and each type can be used an unlimited number of times. The second player has $m$ tile types, also with unlimited supply.
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CF 104377J - BLG冲冲冲！

We are given a full matrix describing the outcome probabilities between every pair of 8 teams. For any two teams $i$ and $j$, the entry $a{i,j}$ gives the probability that $i$ defeats $j$ in a single match, with the complementary probability $a{j,i}$ ensuring that exactly one…
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CF 104377H - 账号已注销，我想账号已注销了

We are given a sequence of $n$ pillars, each with a height. From this sequence we are allowed to choose a non-empty subsequence while preserving the original order. After selecting, we only keep the chosen pillars.
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CF 104377I - 这真的是签到题

We are given a list of integers and asked to select the largest value in that list that satisfies a specific structural property: every prime factor of that value must also appear somewhere in the list.
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CF 104377G - 我的车呢？

We are standing in a 2D plane and there is a hidden point representing a car. We are given one crucial parameter, a radius r, and we can interactively move a point anywhere in the plane and receive a binary answer: whether our current position is within distance r of the…
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CF 104377F - 珂朵莉树

We start with an array of length $n$. The array is repeatedly modified by choosing a random interval $[l, r]$ uniformly among all $frac{n(n+1)}{2}$ possible subsegments, and assigning all elements in that interval a new value that has never been used before.
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CF 104377E - 传感器对齐

We are given two ordered sequences of integers, both of the same length. Each sequence comes from a sensor reading over time, so the index order is fixed and meaningful.
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CF 104377D - 随机数生成器

We are given an array and a random process that repeatedly samples indices uniformly from a chosen segment of this array. After taking k independent samples, we look at the smallest and largest sampled indices and return the sum of the array over that interval.
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CF 104377A - 计算异或和

We are asked to look at all ordered arrays of length $m$ consisting of non-negative integers whose total sum is fixed to $n$. Every such array contributes a value equal to the bitwise XOR of all its elements, and we need the sum of these XOR values over all valid arrays.
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CF 104377C - 二维数组变换

We are given an n by n matrix and a sequence of operations. Each operation selects a square submatrix using its top-left and bottom-right coordinates, then applies one geometric transformation to that submatrix.
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CF 104377B - 最大价值

We are given an undirected graph where each edge carries a weight that behaves like a threshold. You start at node S holding a value k, and want to reach node T.
codeforces competitive-programming Jul 1, 2026