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  • in ACM
  • 1 min read

（转）关于卷积的一个血腥的讲解，看完给跪了

比如说你的老板命令你干活，你却到楼下打台球去了，后来被老板发现，他非常气愤，扇了你一巴掌（注意，这就是输入信号，脉冲），于是你的脸上会渐渐地（贱贱地）鼓起来一个包，你的脸就是一个系统，而鼓起来的包就是你的脸对巴掌的响应，好，这样就和信号系统建立起来意义对应的联系。下面还需要一些假设来保证论证的严谨：假定你的脸是线性时不变系统，也就是说，无论什么时候老板打你一巴掌，打在你脸的同一位置（这似乎要求你的脸足够光滑，如果你说你长了很多青春痘，甚至整个脸皮处处连续处处不可导，那难度太大了，我就无话可说了哈哈），你的脸上总是会在相同的时间间隔内鼓起来一个相同高度的包来，并且假定以鼓起来的包的大小作为系统输出。好了，那么，下面可以进入核心内容——卷积了！

  • in ACM
  • 5 min read

Timus 1996 Cipher Message 3 KMP+FFT求卷积

题目链接：click here

description

Emperor Palpatine has been ruling the Empire for 25 years and Darth Vader has been the head of the Empire Armed Forces. However, the Rebel movement is strong like it never used to be. One of the rebel leaders, Princess Leia from Alderaan, managed to get hold of secret blueprints of the Death Star, the imperial war station.

The Princess was going to deliver the station plan to the secret base for further analysis and searching for vulnerable spots. But her ship was attacked by the space destroyer "Devastator" headed by Darth Vader. At the last moment Princess Leia managed to send her findings to one of the closest planet called Tatooine with her droid R2-D2. Quite conveniently, an old friend of her father Obi-Wan Kenobi lives on that planet.

R2-D2 realizes the importance of his mission. He is going to encrypt the information so that the wrong people won’t get it.

  • in Linux
  • 1 min read

KDE4的配置参考

西北工大回来后,时间又充裕了,所以又开始了折腾KDE。

话说KDE的渲染阴影等效果非常接近MacBook。先放几张图：

抓图14

  • in ACM
  • 2 min read

ACM International Collegiate Programming Contest Asia Regional Contest, Tokyo Problem D Space Golf

原题 pdf：click here

日本的亚洲区域赛真心简单啊。两个小时就刷了 5 题有余了。排名第一的队伍才做出 7 道。

题目真心长的可以了，看了半个小时才明白。。

题意其实也就是太空中向前方抛小球，问小球能够穿过 N 个障碍物后到达制定地点的最小初始速度是多少。非常暴力的模拟题。离散化后直接枚举弹跳的次数再取最小值即可。注意 45° 方向能成功的话，那还是 45° 最优。

  • in Wine
  • 1 min read

优化Wine程序的字体显示

默认Wine的字体太难看，而且有时候还会显示不出来。开启Wine字体的反锯齿及平滑功能以及将字体映射成文泉驿微米黑的方法是：

1.新建文本文件a.reg，放入如下内容：

  • in Linux
  • 1 min read

我的xfce4配置

1.字体：infinally 渲染

2.英文字体：courier prime

3.窗口最大化隐藏标题栏：xfwm4-titleless-dev

4.窗口最大化标题栏隐藏后，在任务栏上显示控制按钮的插件：xfce4-windowck-plugin

  • in ACM
  • 9 min read

HDU 4965 Fast Matrix Calculation

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 131072/131072 K (Java/Others) Total Submission(s): 206    Accepted Submission(s): 116

Problem Description
One day, Alice and Bob felt bored again, Bob knows Alice is a girl who loves math and is just learning something about matrix, so he decided to make a crazy problem for her. Bob has a six-faced dice which has numbers 0, 1, 2, 3, 4 and 5 on each face. At first, he will choose a number N (4 <= N <= 1000), and for N times, he keeps throwing his dice for K times (2 <=K <= 6) and writes down its number on the top face to make an N*K matrix A, in which each element is not less than 0 and not greater than 5\. Then he does similar thing again with a bit difference: he keeps throwing his dice for N times and each time repeat it for K times to write down a K*N matrix B, in which each element is not less than 0 and not greater than 5\. With the two matrix A and B formed, Alice’s task is to perform the following 4-step calculation.
  • in ACM
  • 4 min read

HDU 4945 2048

Time Limit: 3000/1500 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others) Total Submission(s): 590    Accepted Submission(s): 136

Problem Description
Teacher Mai is addicted to game 2048\. But finally he finds it's too hard to get 2048\. So he wants to change the rule: You are given some numbers. Every time you can choose two numbers of the same value from them and merge these two numbers into their sum. And these two numbers disappear meanwhile. If we can get 2048 from a set of numbers with this operation, Teacher Mai think this multiset is good. You have n numbers, A1,...,An. Teacher Mai ask you how many subsequences of A are good. The number can be very large, just output the number modulo 998244353.
  • in ACM
  • 3 min read

HDU 4952 Number Transformation

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others) Total Submission(s): 612    Accepted Submission(s): 310

Problem Description
Teacher Mai has an integer x. He does the following operations k times. In the i-th operation, x becomes the least integer no less than x, which is the multiple of i. He wants to know what is the number x now.