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Contents 1 Members 2 Onsite 3 Online 4 Trainings 4.1 Complete Status (Team Sessions Only) 4.2 Randomly-scheduled Trainings (Fall 2020) 5 Algorithm Trainings 5.1 Math Members Name ID Grade Profession Liang Bao ? 2018 Software Engineering Cunyuan Qiu wuluxun 201Recovered snapshot: 2021-10-26 14:23 UTC
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Archived wiki pageRecovered snapshot: 2025-04-09 05:06 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K Problem A Unsolved. Problem B Unsolved. Problem C Solved by zerol. 00:46 (+) 签到 题意：图像识别 题解：数内部联通块个数 Problem D UnsolveRecovered snapshot: 2025-03-27 18:00 UTC
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Contents 1 NEERC 11 1.1 Problem A 1.2 Problem B 1.3 Problem C 1.4 Problem D 1.5 Problem E 1.6 Problem F 1.7 Problem G 1.8 Problem H 1.9 Problem I 1.10 Problem J 1.11 Problem K 1.12 Problem L NEERC 11 某几题解[solutions] Problem A Solved by dreamcloud. 00:22 题意：签到题Recovered snapshot: 2025-03-27 18:00 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K 12 Problem L Problem A Unsolved. Problem B Solved by zerol. 01:36 (+) 这个才是签到。 Problem C Solved by ultmaster. 02:20 (+Recovered snapshot: 2025-03-27 18:00 UTC
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Contents 1 NEERC 12 1.1 Problem A 1.2 Problem B 1.3 Problem C 1.4 Problem D 1.5 Problem E 1.6 Problem F 1.7 Problem G 1.8 Problem H 1.9 Problem I 1.10 Problem J 1.11 Problem K 1.12 Problem L NEERC 12 某三题题解[solutions] 官方题解[solutions] Problem A Solved by oxx1108Recovered snapshot: 2025-03-27 18:00 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J Problem A Solved by zerol. 00:11 (+) 温暖的签到。 Problem B Solved by ultmaster. 00:38 (+) 就是那个大家都会做的蚂蚁题，但又有点不大一样，反正模拟一下就好了。 Problem C SRecovered snapshot: 2025-04-09 23:39 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K Problem A Unsolved. Problem B Unsolved. Problem C Solved by Weaver_zhu. 01:59 (+) 题意：告诉旋转中心，缩放中心，矩形长宽高和缩放比例，求出一个css的样Recovered snapshot: 2024-07-26 10:52 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K Problem A Unsolved. Problem B Solved by kblack, translated by zerol. 03:51 (+) 题意：双倍汉诺塔，规定最后同大小饼的顺序。 题解：正常移动一堆需要两倍正常汉Recovered snapshot: 2025-03-27 18:00 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K Problem A Solved by dreamcloud. 温暖的签到。 Problem B Unsolved. 瞎随机了四发，没过去。 Problem C Unsolved. Problem D Solved by XiejiaRecovered snapshot: 2024-07-28 18:18 UTC
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听说五题可以上台领奖，恭喜 kblack。 Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K 12 Problem L Problem A Unsolved. Problem B Upsolved by ultmaster. 题意：有 $n$ 种家具，每种家具有无限个。对于离散型的家Recovered snapshot: 2021-12-04 11:30 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K Problem A Solved by oxx1108. 0:15:12 题意：给一个黑白相间的矩形，每次可以选一个子矩阵改变颜色，问至少改变多少次。 题解：改变所有偶数行偶数列即可。 Problem B Solved by XiejRecovered snapshot: 2021-12-08 01:25 UTC
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Contents 1 Problem A 2 Problem B 3 Problem D 4 Problem E 5 Problem H 6 Problem I 7 Problem K Problem A Solved by zerol. 00:32 (+1) 温暖的签到。但是我把 m 打成 n 了。。。 Problem B Solved by ultmaster. 03:48 (+) 题意：在树上装两盏半径为 $r$ 的路灯，要求覆盖整棵树。求最小的 $r$。 题解：我们大概可以猜出这两盏路灯一定装在直径的第 $Recovered snapshot: 2025-03-27 18:00 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I Problem A Solved by zerol. 00:23 (+) 温暖的签到 Problem B Solved by zerol. 00:12 (+) 温暖的签到 Problem C Solved by ultmaster. 00:31 (+) 题意：从一条直线的一端走到另一端Recovered snapshot: 2025-03-27 18:00 UTC
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特别简单、特别适合双开的场。 Contents 1 Problem C 2 Problem D 3 Problem E 4 Problem F 5 Problem G 6 Problem H 7 Problem I 8 Problem J 9 Problem K Problem C Solved by ultmaster. 00:38 (+1) 题意：超市买东西价格四舍五入，要求在物品之间插隔板尽可能逃钱。 题解：某人没有注意到是已经排好序的，想了半天贪心。然后，就没什么好说的了。 Problem D SolvedRecovered snapshot: 2021-12-05 22:45 UTC
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ultmaster: 久违地达到了平均贡献。 Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem G 6 Problem J Problem A Solved by kblack. 00:25 (+1) 略带凉意的签到。 Problem B Solved by ultmaster. 03:07 (+) 题意：给 50 个长度为 20 的字符串。字符串有些位置被挖掉了。让你把挖掉的位置填上使得组成一个有序的各不相同的字符串序列。问有多少Recovered snapshot: 2024-07-27 08:42 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K Problem A Solved by Xiejiadong. 01:24:36(+) 题意：沿$x$轴把沙漠分成两块，使得两边的绿地面积之差最小。 题解：根据给出的绿地坐标，在开始位置和结束位置分别打上tag，然后枚举所有的分割点，Recovered snapshot: 2021-09-29 01:55 UTC
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Problem A Solved by Weaver_zhu. 00:32 (+) 数位dp基础题 Problem B Unsolved. Problem C Solved by Xiejiadong && Kilo_5723. 01:02 (+1) 题意：数列的前两项是 1, 2，后面每一项都是与前一项不互素且在之前的数列中未出现过的最小数字。 题解：显然，数列中的每一项都是一个质数的倍数，我们用所有的质数来维护一个队列，表示当前质数所到的最小倍数。 对于第$n$项，我们只需要对于$n-1$的质因数，然后在所有的Recovered snapshot: 2024-09-22 00:00 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J Problem A Solved by zerol. 00:22 (+) 题意：问有多少个小于等于给定的数满足每一位上的数大于等于一个数字。 题解：数位 DP 签到。 Problem B Unsolved. Problem C Solved by zerol.Recovered snapshot: 2021-12-04 09:53 UTC
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_ Xiejiadong: 抱着能 AK 的幻想。最后一个小时还是三人三线开题。三人枪机，三人三爆炸。 Problem A Upsolved by Weaver_zhu 题意：一个三位空间中维护计算任一点在整数时间点相遇，坐标对数取模。 题解：数据范围可以支持不停的$n^2$判断相撞，然后直到撞不了为止。剩下的就是解模线性方程组。坑点是各种无解的情况（模数都不是互素的，一个维上坐标不变，可以是一直重合和一直相离的情况） Problem B Solved by Weaver_zhu. 02:17 (+1) 题意：把黑Recovered snapshot: 2024-09-22 00:00 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I Problem A Unsolved. Problem B Upsolved by zerol. (-7) 题意：就是屏幕里有一些像素，像素分成两类 A B，问最少的移动次数，使得所有 A 在一个矩形区域内且所有 B 在区域外。 题解：就是枚举可能的矩形，然后计算答案。以 x 轴为例，Recovered snapshot: 2021-12-06 00:10 UTC
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三人三机。做了三个小时摸了。 Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K 12 Problem L Problem A Solved by kblack. 00:34 (+1) 行列分别统计即可，没写文件贡献一发罚时。 Problem B Solved by ultmasterRecovered snapshot: 2024-11-11 00:24 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem E 5 Problem F 6 Problem I 7 Problem H 8 Problem J 9 Problem K Problem A Upsolved by ultmaster. 2018 Multi-University, HDU Day 4 的 A 的一个温暖版。 Problem B Upsolved by zerol. (-2) 题意：求一个最大的 $D$，使得在只有大于等于 $D$ 的点才Recovered snapshot: 2021-12-05 23:43 UTC
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Contents 1 Problem A 2 Problem D 3 Problem E 4 Problem F 5 Problem G 6 Problem H 7 Problem I 8 Problem J Problem A Solved by zerol. 01:19 (+3) 题意：求一个矩阵的秩。 题解：某人因为坐地铁迟到了。但迟到了这么久，队友居然签到都没成功。取模真的是套路啊！为什么要调 EPS 呢…… Problem D Upsolved by zerol. 题解 Problem E SolvedRecovered snapshot: 2024-07-26 15:20 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem E 5 Problem F 6 Problem G 7 Problem H Problem A Upsolved by kblack. 题意：若干工厂按比例需要其他某些工厂的产品，生产的产品可以分给别的工厂或销售，已知去年销售和互相供货的量，求按今年销量的需求每个工厂总共需要生产多少产品。 题解：显然的方程组复杂度过高，直接考虑迭代松弛即可。 注：使用 C++14 会无故超时，见鬼了！ Problem BRecovered snapshot: 2021-12-04 10:45 UTC
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Contents 1 ECNU Foreigners 1.1 Problem A 1.2 Problem F 1.3 Problem G 1.4 Problem H 1.5 Problem I 1.6 Problem J 1.7 Problem K 2 One,Two,Three,AK 2.1 Problem A 2.2 Problem B 2.3 Problem C 2.4 Problem D 2.5 Problem E 2.6 Problem F 2.7 Problem G 2.8 Problem H 2.9Recovered snapshot: 2021-09-29 01:02 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem I 8 Problem J 9 Problem K Problem A Upsolved by kblack. 题意：环上 $n$ 个点，要求造 $k$ 个集中点，每个点分配到一个集中点以后，集中点到分配的点的距离和的最大值最小。 题解：显然二分最大值，考虑如何验证。先把环变成两份，可以通过前缀和快速地求从某个点开始，往右最多吃到 $rRecovered snapshot: 2021-12-04 11:42 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K 12 Problem L 13 Problem M Problem A Solved by zerol. 04:30 (+1) CF 突然炸了。就交在 kattis 上了。 题意：有一些糖果，每个糖果有一个比例，对于任意前若干天，天数Recovered snapshot: 2021-12-06 00:10 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K Problem A Upsolved by Xiejiadong. 题意：给 $n$ 个串，有两种操作，一种是给某个串加一个字符，另一种是求存不存在一个串是查询串的子串。强制在线。 题解：由于限制了总长，所以不同的长度不会太多（根号级Recovered snapshot: 2024-07-29 08:07 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem I 9 Problem J 10 Problem K Problem A Solved by ultmaster. 04:51 (+4) 题意：给 $n$ 个串，有两种操作，一种是给某个串加一个字符，另一种是求存不存在一个串是查询串的子串。强制在线。 题解：由于限制了总长，所以不同的长度不会太多（根号级别）。枚举Recovered snapshot: 2021-12-06 00:01 UTC
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Contents 1 Problem A 2 Problem E 3 Problem F 4 Problem G 5 Problem H 6 Problem J Problem A Solved by ultmaster. 01:55 (+2) 题意：模拟题。大概就是把某些连续的东西替换成缩写，之类的。 题解：据说用正则表达式一行就能解决。我用 Python 写了好多好多行，怕不是傻逼。。。 Problem E Solved by kblack. 02:18 (+) 温暖的签到。 Problem F SolvedRecovered snapshot: 2021-12-04 09:46 UTC
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Contents 1 Foreigners 1.1 Problem A 1.2 Problem B 1.3 Problem C 1.4 Problem D 1.5 Problem E 1.6 Problem F 1.7 Problem G 1.8 Problem H 1.9 Problem I 1.10 Problem J 1.11 Problem K 1.12 Problem L 1.13 Problem M 2 oxx1108 2.1 Problem A 2.2 Problem B 2.3 Problem CRecovered snapshot: 2021-12-04 10:42 UTC
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Contents 1 Website 2 Problem A 3 Problem B 4 Problem C 5 Problem D 6 Problem E 7 Problem F 8 Problem G 9 Problem H 10 Problem I 11 Problem J 12 Problem K Website https://vjudge.net/contest/250470#overview Problem A Solved by dreamcloud.00:08:07 题意：超级签到题，1至n，任意Recovered snapshot: 2021-09-29 01:43 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J Problem A Solved by ultmaster. 04:33 (+) 题意：求多个简单多边形的并。 题解（伪）：以多边形的点和多边形与多边形的交点作为关键 $x$ 点进行离散化。然后算出每一段区间内的关键 $y$ 点扫描线即可。 貌似可以随便卡掉？Recovered snapshot: 2024-07-26 03:45 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K Problem A Solved by kblack. 03:43 (+1) 题意：给三种颜色 $N$ 个点，要求搞两个不相交的多边形，使得每种颜色被隔开。 题解：上下分别开一个矩形当总线，当一列中有点需要接收时，拉一个矩形上去，分别Recovered snapshot: 2022-01-16 09:54 UTC
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Contents 1 ECNU Foreigners 1.1 Problem A 1.2 Problem B 1.3 Problem C 1.4 Problem D 1.5 Problem E 1.6 Problem F 1.7 Problem G 1.8 Problem H 1.9 Problem I 1.10 Problem J 1.11 Problem K 1.12 Problem L 1.13 Problem M 2 One,Two,Three,AK 2.1 Problem A 2.2 Problem BRecovered snapshot: 2021-09-29 01:09 UTC
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Contents 1 ECNU Foreigners 1.1 Problem A 1.2 Problem B 1.3 Problem C 1.4 Problem D 1.5 Problem E 1.6 Problem F 1.7 Problem G 1.8 Problem H 1.9 Problem I 1.10 Problem J 1.11 Problem K 1.12 Problem L 2 One,Two,Three,AK 2.1 Problem A 2.2 Problem B 2.3 Problem C 2Recovered snapshot: 2021-09-29 02:21 UTC
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Contents 1 Problem A 2 Problem F 3 Problem G 4 Problem H 5 Problem J 6 Problem K 7 Problem L Problem A Solved by ultmaster. 02:48 (+) 题意：飞机上选座位的模拟题。 题解：某人情境代入了，搞反了左右。（当然为什么会情境代入呢？主要是因为没读清楚题。） Problem F Solved by ultmaster & zerol. 03:20 (+13) 题意：定义一种新阶乘是 1 乘到Recovered snapshot: 2021-12-04 10:53 UTC
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菜得不行。 Contents 1 Problem A 2 Problem C 3 Problem D 4 Problem J 5 Problem K 6 Problem L Problem A Solved by ultmaster. 01:22 (+2) 题意：$a$, $b$, $c$ 是递增数列，求 $(i,j,k)$ 对数满足 $|a_i-b_j| \le d, |a_i-c_k| \le d, |b_j-c_k| \le d$。 题解：枚举 $a$ 中的元素，$b$ 中满足的显然是一个区间，对于这个区间内Recovered snapshot: 2024-07-27 18:36 UTC
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由于选题人的失误这场没有配置题解，也没有相应的 wiki。可能要当第一个。（似乎本 wiki 根本没有被搜索引擎收录，凉凉。） 这场有一半的题是 kblack 做的。ultmaster 只做了一个签到题。之所以能贡献这一个签到题似乎是因为数据炸了。 Contents 1 Problem A 2 Problem D 3 Problem F 4 Problem G 5 Problem J 6 Problem K Problem A Solved by ultmaster. 02:22 (+2) 题意：求一个串有多少种方Recovered snapshot: 2021-12-04 11:43 UTC
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Contents 1 Replay 2 Problem A 3 Problem B 4 Problem C 5 Problem D 6 Problem E 7 Problem F 8 Problem G 9 Problem H 10 Problem I 11 Problem J Replay oxx1108: 打崩了 会做的题没时间做了 dreamcloud: Xiejiadong: 北大的肯德基真好吃。 签到罚时，甩锅 气球是氦气球，好评，不过气球怎么老是漏气啊 餐券用到用不完，甚至还送了隔壁队90多 ProblRecovered snapshot: 2024-08-11 21:16 UTC
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Contents 1 Replay 2 Problem A 3 Problem B 4 Problem C 5 Problem D 6 Problem E 7 Problem F 8 Problem G 9 Problem H 10 Problem I 11 Problem J 12 Problem K 13 Problem L 14 Problem M Replay oxx1108: 垃圾比赛，毁我青春。 全场副作用，贡献了6发罚时。 唯一欣慰的是可以嘲笑对面要吊打咖啡鸡的队伍。 dreamcloud: XiejRecovered snapshot: 2021-09-29 02:24 UTC
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Contents 1 One,Two,Three,AK 1.1 Problem A 1.2 Problem B 1.3 Problem C 1.4 Problem D 1.5 Problem E 1.6 Problem F 1.7 Problem G 1.8 Problem H 1.9 Problem I 1.10 Problem J 1.11 Problem K 1.12 Problem L 1.13 Problem M One,Two,Three,AK Xiejiadong:罚时的锅全是我的。 ProblemRecovered snapshot: 2021-09-29 02:12 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K 12 Problem L Problem A Solved by zerol. 01:21 (+) 题意：求一条直线，至少经过 N 个点中的 N * k 个点，$(0.1 \leq k \leq 0.9)$。 题解：随机挑两个点，如果Recovered snapshot: 2021-12-04 11:09 UTC
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Contents 1 杂事 1.1 ultmaster 1.2 zerol 1.3 kblack 2 Problem A 3 Problem B 4 Problem C 5 Problem D 6 Problem E 7 Problem F 8 Problem G 9 Problem H 10 Problem I 11 Problem J 12 Problem K 杂事 ultmaster $pc^2$ 差评。 一直 Compilation Error。然后重测了一下 CE 变 WA 了。 做得非常不顺，前期一直在Recovered snapshot: 2021-12-05 23:01 UTC
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Contents 1 Replay 2 Problem C 3 Problem E 4 Problem G 5 Problem I 6 Problem J 7 Problem K 8 Problem L 9 Problem M Replay ultmaster: 热身赛阻碍了个 kblack 的 AK 进程。暗示了正赛的剧情。 听说比多校还难。 强制穿衣服的操作有点傻逼。而且衣服还没有去年好看，甚至是中老年保暖衣。:( 比赛还没开始就发了题目和密码条。题目没有信封。计算机没有锁屏。有点牛逼。 好在也没什么题能做，并Recovered snapshot: 2025-03-31 21:56 UTC
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Contents 1 Replay 2 Problem C 3 Problem E 4 Problem G 5 Problem I 6 Problem J 7 Problem K 8 Problem L 9 Problem M Replay ultmaster: 热身赛阻碍了个 kblack 的 AK 进程。暗示了正赛的剧情。 听说比多校还难。 强制穿衣服的操作有点傻逼。而且衣服还没有去年好看，甚至是中老年保暖衣。:( 比赛还没开始就发了题目和密码条。题目没有信封。计算机没有锁屏。有点牛逼。 好在也没什么题能做，并Recovered snapshot: 2025-04-01 09:51 UTC
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Contents 1 Replay 2 Problem A 3 Problem C 4 Problem D 5 Problem F 6 Problem G 7 Problem H 8 Problem I 9 Problem M Replay zerol: 来了 ultmaster: 只做了半道题是怎么回事啊？ 赛后发现傻逼题还不如不要发现呢。难受 QAQ~ WF 顺位 3，岌岌可危。（然而已经没救了 食堂又远又不好吃。 出租车坑。 要不是这个比赛我有可能永远都不会听说矿大这个学校。 回想了一下这好像是第二次有教练跟Recovered snapshot: 2021-12-05 22:52 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K Problem A Solved by Weaver_zhu. 0:10 (+) 温暖的签到 Problem B Solved by Kilo_5723. 0:54 (+1) 题意：办公室内有一些人，这些人有生日。现在你想把你的生日安Recovered snapshot: 2024-07-26 16:04 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem F 5 Problem G 6 Problem I 7 Problem J 8 Problem K Problem A Solved by ultmaster. 00:17 (+) 在 $n$ 个数里选尽可能多的数，使得没有两个数加起来超过 $x$。 Problem B Solved by zerol. 01:57 (+) 蛋疼模拟题意。毫无技巧。 Problem C Solved by ultmasterRecovered snapshot: 2024-07-26 22:21 UTC
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Contents 1 Replay 2 Problem A 3 Problem B 4 Problem C 5 Problem D 6 Problem E 7 Problem F 8 Problem G 9 Problem H 10 Problem I 11 Problem J 12 Problem K 13 Problem L Replay oxx1108: dreamcloud: Xiejiadong: 座位正好在志愿者边上，比赛前偷偷看了气球，发现黑球巨多，于是猜到了G是签到 上来oxx暴切G，差点一血 H没Recovered snapshot: 2025-04-09 23:33 UTC
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Contents 1 Replay 2 Problem A 3 Problem B 4 Problem C 5 Problem D 6 Problem E 7 Problem F 8 Problem G 9 Problem H 10 Problem I 11 Problem J 12 Problem K 13 Problem L Replay oxx1108: dreamcloud: Xiejiadong: 座位正好在志愿者边上，比赛前偷偷看了气球，发现黑球巨多，于是猜到了G是签到 上来oxx暴切G，差点一血 H没Recovered snapshot: 2021-10-19 12:05 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K 12 Problem L Problem A Solved by Weaver_zhu. 00:07:11 (+) Problem B Solved by Xiejiadong. 00:45:37 (+2) 题意：要求在四个城市之间完Recovered snapshot: 2021-12-09 01:48 UTC
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Contents 1 One,Two,Three,AK 1.1 Problem A 1.2 Problem B 1.3 Problem C 1.4 Problem D 1.5 Problem E 1.6 Problem F 1.7 Problem G 1.8 Problem H 1.9 Problem I 1.10 Problem J 2 ECNU Foreigners 2.1 Problem A 2.2 Problem B 2.3 Problem C 2.4 Problem D 2.5 Problem E 2.6Recovered snapshot: 2021-09-29 00:57 UTC
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Contents 1 Replay 2 Problem A 3 Problem B 4 Problem C 5 Problem D 6 Problem G 7 Problem I 8 Problem J Replay ultmaster: 忘记 break，甚至成功拉着一个队友一起自闭。比赛一开始就觉得自己凉了真是常见呢。 D 是假的。但奖杯是真的。真香预警。 题目不是 LaTeX 的，差评。 6 个签到签完，神仙题四选一。 早班飞机要两天的睡眠才能补回来。 zerol: 起手签了个到，好在没锅，真的好怕签到背锅。Recovered snapshot: 2024-06-06 05:09 UTC
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Redirect to:2018 CCPC Online ContestRecovered snapshot: 2024-06-06 20:48 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K 12 Problem L Problem A Solved by Xiejiadong. 00:12 (+1) 温暖的排序签到。 +1 是因为煞笔了。 Problem B Solved by Kilo_5723. 04:20 (+)Recovered snapshot: 2022-07-06 00:09 UTC
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Contents 1 One,Two,Three,AK 1.1 Problem A 1.2 Problem B 1.3 Problem C 1.4 Problem D 1.5 Problem E 1.6 Problem F 1.7 Problem G 1.8 Problem H 1.9 Problem I 1.10 Problem J 1.11 Problem K 1.12 Problem L One,Two,Three,AK 自不量力的Xiejiadong去刚J这道数学题，浪费了大量时间搞假算法，背大锅。 ProRecovered snapshot: 2021-09-29 00:55 UTC
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Contents 1 2018 ECNU One,Two,Three,AK's ICPC/CCPC Training Contest 1.1 Date 1.2 Comment 1.2.1 题目来源以及难度 1.2.2 补题建议 1.3 Problem A 1.4 Problem B 1.5 Problem C 1.6 Problem D 1.7 Problem E 1.8 Problem F 1.9 Problem G 1.10 Problem H 1.11 Problem I 1.12 Problem J 1.1Recovered snapshot: 2024-08-11 07:53 UTC
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Archived wiki pageRecovered snapshot: 2024-07-27 21:50 UTC
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Problem A Solved by Kilo_5723. 00:59:24 (+) Problem B Solved by Xiejiadong. 00:35:08 (+) 题意：可以在 $n$ 个点中选择一个点作为信号基站，信号的传递是跳边（间隔传递）的，求添加最小数量的边，使得消息传遍全图。 题解：显然如果图中有 $n$ 个联通块，我们需要用 $n-1$ 条边将他们连接起来。 而此时无法把信息传遍全图的情况，只剩下了，这张图是二分图的情况。显然在不同联通块之间加边并不会影响是否是二分图，直接判断即可。 PrRecovered snapshot: 2024-09-22 00:00 UTC
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Contents 1 ECNU Foreigners 1.1 Replay 1.2 Problem A 1.3 Problem C 1.4 Problem D 1.5 Problem F 1.6 Problem H 1.7 Problem I 1.8 Problem J 1.9 Problem L 2 One,Two,Three,AK 2.1 Replay 2.2 Problem C 2.3 Problem D 2.4 Problem F 2.5 Problem G 2.6 Problem I 2.7 ProbleRecovered snapshot: 2025-04-09 23:35 UTC
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Contents 1 2018 ICPC Mid-Central Regional 1.1 Problem A 1.2 Problem B 1.3 Problem C 1.4 Problem D 1.5 Problem E 1.6 Problem F 1.7 Problem G 1.8 Problem H 1.9 Problem I 1.10 Problem J 1.11 Problem K 2018 ICPC Mid-Central Regional Xiejiadong : 趁着队友还没睡醒，抢的一手签到题。Recovered snapshot: 2022-01-27 14:40 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K Problem A Upsolved by kblack. 题意：一个 $R \times C$ 的四消游戏，每次可以放一对相邻的珠子（上下或左右），需要在规定步数内造出指定图形。 题解：如果一列有偶数个，从下往上慢慢堆总是好的，奇数Recovered snapshot: 2022-01-21 07:21 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J Problem A Solved. 题意：选择三个数$x$,$y$,$z$，使得$x+y+z=n$并且$x|n$,$y|n$,$z|n$,要求$x*y*z$最小。 题解：显然，$x$,$y$,$z$三个数越接近越优秀 那么当我们根据$1=\frac{1}{3}Recovered snapshot: 2020-10-28 00:33 UTC
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Contents 1 Problem A 2 Problem C 3 Problem E 4 Problem G 5 Problem H 6 Problem I 7 Problem J 8 Problem L Problem A Unsolved. Problem C Unsolved. Problem E Solved. 题意：对于树上的每个点，求 lca 恰好是这个点的点对中点权 gcd 的最大值。 题解：对于树上每个点，求出一个 bitset 记录了子树中所有数的因数并，然后依次合并儿子以及自己本身，合并前取Recovered snapshot: 2021-09-29 01:11 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J Problem A Unsolved. Problem B Unsolved. Problem C Xiejiadong：就靠着这一题，多校打到了人生巅峰，一个人碾压一队。 Solved. 题意：给一个无向图，求用最少的路径（可以非简单），覆盖无向图的所有边。Recovered snapshot: 2021-09-29 02:13 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem K Problem A Solved by ultmaster. 00:41 (+2) 题意：求 $a$, $b$, $c$ 满足都是 $n$ 的因数也和为 $n$。 题解：各种筛各种暴力发现都布星。过了好久才开始考虑数学性质，好像只能分成 1/3 * 3 或者 1/2 + 1/4 + 1Recovered snapshot: 2022-01-16 11:17 UTC
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Contents 1 Problem A 2 Problem C 3 Problem E 4 Problem G 5 Problem H 6 Problem I 7 Problem J 8 Problem L Problem A Upsolved by ultmaster. 题意：求烷烃、烷基的同分异构体数量。 题解：仔细论证 / OEIS 可以得到烷基个数有生成函数 $A(x) = 1 + \frac{1}{6}x (A(x)^3 + 3A(x)A(x^2) + 2A(x^3)$。用分治 FFT 可以解 $A(xRecovered snapshot: 2021-12-04 10:47 UTC
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Contents 1 Problem A 2 Problem C 3 Problem D 4 Problem E 5 Problem F 6 Problem G 7 Problem J Problem A Upsolved by ultmaster. 题意：有一堆随机变量 $x_1,\ldots,x_n$，其中 $x_i \sim U(l_i,r_i)$。求 $|x_1+\cdots+x_n|$ 的期望。 题解：官方题解给的解法一，尝试实现，两个小时后放弃。而解法二，说实话，写得太过意识流了。 其实两个解法都把题意Recovered snapshot: 2022-01-16 11:17 UTC
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Contents 1 Problem A 2 Problem C 3 Problem D 4 Problem F 5 Problem G 6 Problem H 7 Problem I 8 Problem J 9 Problem L 10 Problem M Problem A Solved by kblack. 01:45 (+5) 题意：在长度为 $n$，部分随机的序列中，求大小为 $m$ 的滑动窗口滑过的每个区间的最大值及最大值变化次数。 题解：从后往前即可获得每个数的下一跳，再正着并查集维护即可。辣鸡出题人Recovered snapshot: 2022-01-16 11:17 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K 12 Problem L Problem A Upsolved by ultmaster. 题意：一个数是好数当且仅当比它小的且因数个数比它多的数不超过 $K$ 个。求第 $n$ 个不好的数。 题解：此题是一个之前没补的题：2015-Recovered snapshot: 2024-07-27 15:29 UTC
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卡常卡得真刺激。 kblack: 按去年青岛，35 个金，三题手速金，传奇再现。 zerol：零贡献。被 TLE 和 MLE 搞自闭了。 Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K 12 Problem L Problem A Upsolved by kblack. 题意：给一Recovered snapshot: 2022-01-16 11:20 UTC
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ultmaster: 除了我签了个到，全是 kblack 做的。可能 kblack 1v3 结局也差不多吧。。。 Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K 12 Problem L Problem A Solved by ultmaster. 00:39 (+4) 题意：小学Recovered snapshot: 2024-07-26 01:15 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K Problem A Solved by kblack. 01:47 (+2) 题意：给一个边上带颜色的无向图，走的边颜色变化一次花 1，求最短路。 题解：边上加个点，到两个端点距离为 1，一个点出去的同色边缩一下，因为距离都是 1，跑Recovered snapshot: 2021-12-04 11:33 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K 12 Problem L Problem A Solved by zerol. 00:41 (+1) 题意：求 $\sum_{i=1}^m x_i = k$ ($0 \le x_i < n$) 的整数解的组数。 题解：如果只有限制 $Recovered snapshot: 2024-07-25 14:41 UTC
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两个半小时签完到，最后两个 Last Hour。人生大起大落真刺激。 Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem J 6 Problem K Problem A Solved by zerol & kblack. 02:33 (+) 题意：在 n×m 的方格中填 1~nm 的数，使得只有一个数是它所在行列的最大值。 题解：显然那唯一一个数就是 nm。考虑从大到小依次填数，每个数肯定得填在一个之前填过的数的同一行或者同一列。dpRecovered snapshot: 2024-07-27 23:16 UTC
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如果要看代码的话，请移步 铁牌选手K 的提交。 数数题超多。 zerol 和 kblack 负责做难题，ultmaster 负责找规律和使用搜索引擎。 Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J Problem A Solved by ultmaster. 02:39 (+) 题意：往 $n \timeRecovered snapshot: 2021-12-04 10:02 UTC
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Contents 1 Problem A 2 Problem D 3 Problem E 4 Problem F 5 Problem H 6 Problem J Problem A Solved by kblack. 00:23 (+) 题意：随机修改范围内的 $x$ 为 $x+lowbit(x)$ 或 $x-lowbit(x)$，求区间和期望。 题解：假题。。。修改操作不改变期望。。。 Problem D Solved by ultmaster. 01:20 (+1) 题意：有三种操作，区间加，对整个序列求前缀和Recovered snapshot: 2024-06-03 19:11 UTC
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摸了待补。Recovered snapshot: 2021-12-07 02:39 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J Problem A Solved by kblack. 01:16 (+1) 题意：容量是四元组，求限制内最大价值和。 题解：将物品分为两半，每半用 $2^{18}$ 枚举，然后耗费 $36^4$ 更新一遍，处理没有用完限制的部分。 Problem B UpsRecovered snapshot: 2021-12-07 02:56 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J Problem A Solved by zerol. 02:17 (+2) 题意：给一个 012 的字符串，每过一个单位时间 1->10, 2->21 并且移除第一个字符。问最后变成空串会需要多少时间。 题解：写个递推式（大概很简单？），发现需要对 2 递归地Recovered snapshot: 2021-12-04 11:05 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J Problem A Solved by ultmaster. 00:25 (+) 题意：要求删掉 $k$ 门课程的成绩使得加权平均分最大。 题解：二分答案，移项后判断式子是否大于 0 即可。 Problem B Upsolved by ultmaster. 题Recovered snapshot: 2020-08-09 06:30 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J Problem A Solved by zerol. 00:34 (+) 题意：$2^n$ 个人按完全二叉树进行比赛，每轮用掉 n 个数中的一个，大的获胜，问胜者是谁。 题解：模拟。每次胜者用掉比对方最大的更大一些的数。 Problem B UpsolvedRecovered snapshot: 2025-04-10 00:01 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J Problem A Solved by zerol. 00:22 (+) 题意：求一个 1~n 到 1~n 的匹配，使得位与的和最小。 题解：首先猜想答案一定是 0（考虑每一位，0 的个数都不小于 1 的个数，所以不排除答案是 0 的可能性）。然后开始构造，发Recovered snapshot: 2021-12-04 10:15 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K Problem A Problem B Solved by OEIS. 01:12 (+) Brute force by ultmaster. 题意：染棋盘上不同行不同列的 $n$ 个格子，使得经过一系列两个相邻格子都染黑则染黑的操作Recovered snapshot: 2022-01-16 10:11 UTC
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Contents 1 Problem A 2 Problem C 3 Problem D 4 Problem E 5 Problem F 6 Problem G 7 Problem H Problem A Solved by zerol. 02:10 (+) 题意：已知 a 和 x 的 FWT 结果是 b，输入 a 和 b，求 x。 求解 $Ax=b \pmod p$，其中 $A_{ij}=a[i \oplus j]$。（n 恰好是 2 的幂） 题解：将 A x b 都分块，A 分成 4 块，其中左上右下以及左下右Recovered snapshot: 2021-12-04 10:54 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J Problem A Solved. 题意：往 n×m 的格子里填 0,1,2，求左边比右边小，上面比下面小的填法数量。 题解：显然，就是求分界线0/1和1/2不相交的方案数，不会啊..... 是什么Lindström–Gessel–Viennot定理？直接找规Recovered snapshot: 2021-01-19 14:29 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K Problem A Solved. 题意： 题解： Problem B Unsolved. 题意： 题解： Problem C Unsolved. 题意： 题解： Problem D Solved. 题意：三个操作，一个操作是求区间和Recovered snapshot: 2021-01-19 14:47 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K Problem A Solved by 题意： 题解： Problem B Solved by 题意： 题解： Problem C Unsolved. 题意： 题解： Problem D Unsolved. 题意： 题解： ProblRecovered snapshot: 2021-09-29 01:28 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K Problem A Solved by 题意： 题解： Problem B Solved by 题意： 题解： Problem C Unsolved. 题意： 题解： Problem D Unsolved. 题意： 题解： ProblRecovered snapshot: 2021-09-29 01:12 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K Problem A Solved by 题意： 题解： Problem B Solved by 题意： 题解： Problem C Unsolved. 题意： 题解： Problem D Unsolved. 题意： 题解： ProblRecovered snapshot: 2021-01-19 15:42 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K Problem A Solved by 题意： 题解： Problem B Solved by 题意： 题解： Problem C Unsolved. 题意： 题解： Problem D Unsolved. 题意： 题解： ProblRecovered snapshot: 2021-09-29 02:41 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K Problem A Solved by 题意： 题解： Problem B Solved by 题意： 题解： Problem C Unsolved. 题意： 题解： Problem D Unsolved. 题意： 题解： ProblRecovered snapshot: 2021-09-29 02:27 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K Problem A Solved by 题意： 题解： Problem B Solved by 题意： 题解： Problem C Unsolved. 题意： 题解： Problem D Unsolved. 题意： 题解： ProblRecovered snapshot: 2021-09-29 02:14 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K Problem A Solved by 题意： 题解： Problem B Solved by 题意： 题解： Problem C Unsolved. 题意： 题解： Problem D Unsolved. 题意： 题解： ProblRecovered snapshot: 2021-09-29 02:00 UTC
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Contents 1 Problem A 2 Problem B 3 Problem C 4 Problem D 5 Problem E 6 Problem F 7 Problem G 8 Problem H 9 Problem I 10 Problem J 11 Problem K Problem A Solved by 题意： 题解： Problem B Solved by 题意： 题解： Problem C Unsolved. 题意： 题解： Problem D Unsolved. 题意： 题解： ProblRecovered snapshot: 2021-09-29 01:46 UTC
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ultmaster Problem D 题意：给一张贴好的邮票。问有哪些小邮票最后可以贴出这个图案。 题解：枚举所有子串。然后 check。check 的方法：题解的没看懂，自己想了一种：$dp(i+1,0)$ 表示到 $i$ 为止，左边的那段还没结束，也就是说不能接一段中间开始的（一定要接从头开始的）。可行为 1，不可行为 0；$dp(i+1,1)$ 表示到 $i$ 为止，左边的那段已经结束，可以接一段从中间开始的。这个一定要画个图理解一下！刚开始 $dp(0,0)=1$，最后如果 $dp(n,1)=1$ 则可行Recovered snapshot: 2024-07-25 23:44 UTC
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Contents 1 ultmaster 1.1 Problem D 1.2 Problem F 2 kblack 2.1 Problem D ultmaster Problem D ultmaster 的套路： 小的时候暴力，排个序。 大的时候肯定可以，所以随机。 Problem F 想到不敢写，于是就错过了。ultmaster 好像不大会输出直径。 kblack Problem D kblack 的套路： 区间有延展性，所以可以尺取。 简单观察发现如果可以组成三角形，一定有大小连续的三个可以组成，插入删除复杂度Recovered snapshot: 2024-07-26 02:27 UTC
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Problem ARecovered snapshot: 2024-09-22 00:00 UTC