雪之精灵

从吐丝结茧到破茧而出

2010年6月12日 #

Ubuntu 8.04 source

sudo cp /etc/apt/sources.list /etc/apt/sources.list_backup 备份现有更新源
sudo gedit /etc/apt/sources.list    编辑更新源列表
从下面各服务器列表内容中选择一段替换文件中的所有内容
保存编辑好的文件,执行以下命令更新。
sudo apt-get update (修改sources.list后必须运行!)
sudo apt-get dist-upgrade (更新所有软件)
# Shanghai Jiaotong Unverisity. APT source for Ubuntu 8.04 (hardy heron)
deb http://ftp.sjtu.edu.cn/ubuntu/ hardy main multiverse restricted universe
deb http://ftp.sjtu.edu.cn/ubuntu/ hardy-backports main multiverse restricted universe
deb http://ftp.sjtu.edu.cn/ubuntu/ hardy-proposed main multiverse restricted universe
deb http://ftp.sjtu.edu.cn/ubuntu/ hardy-security main multiverse restricted universe
deb http://ftp.sjtu.edu.cn/ubuntu/ hardy-updates main multiverse restricted universe
deb-src http://ftp.sjtu.edu.cn/ubuntu/ hardy main multiverse restricted universe
deb-src http://ftp.sjtu.edu.cn/ubuntu/ hardy-backports main multiverse restricted universe
deb-src http://ftp.sjtu.edu.cn/ubuntu/ hardy-proposed main multiverse restricted universe
deb-src http://ftp.sjtu.edu.cn/ubuntu/ hardy-security main multiverse restricted universe
deb-src http://ftp.sjtu.edu.cn/ubuntu/ hardy-updates main multiverse restricted universe

# University of Science and Technology of China. APT source for Ubuntu 8.04 (hardy heron)
deb http://debian.ustc.edu.cn/ubuntu/ hardy main multiverse restricted universe
deb http://debian.ustc.edu.cn/ubuntu/ hardy-backports main multiverse restricted universe
deb http://debian.ustc.edu.cn/ubuntu/ hardy-proposed main multiverse restricted universe
deb http://debian.ustc.edu.cn/ubuntu/ hardy-security main multiverse restricted universe
deb http://debian.ustc.edu.cn/ubuntu/ hardy-updates main multiverse restricted universe
deb-src http://debian.ustc.edu.cn/ubuntu/ hardy main multiverse restricted universe
deb-src http://debian.ustc.edu.cn/ubuntu/ hardy-backports main multiverse restricted universe
deb-src http://debian.ustc.edu.cn/ubuntu/ hardy-proposed main multiverse restricted universe
deb-src http://debian.ustc.edu.cn/ubuntu/ hardy-security main multiverse restricted universe
deb-src http://debian.ustc.edu.cn/ubuntu/ hardy-updates main multiverse restricted universe

posted @ 2010-06-12 15:43 雪之精灵 阅读(315) | 评论 (0)编辑 收藏

2010年6月4日 #

Suggestions for presentations about reading academic paper

1. Plan to spend 30-40 minutes on the talk (10 minutes of motivation, 10 minutes explaining the main idea and results, 10 minutes summarizing the paper and providing your perspective.)
2. This will leave 10-15 minutes for a discussion on the topic. At the end of the discussion, we should have answered some of the following questions:

  Why is this a significant problem?
  Are there alternate approaches to solve this problem?
  Can we improve the techniques proposed in the paper?

posted @ 2010-06-04 13:16 雪之精灵 阅读(138) | 评论 (0)编辑 收藏

2010年5月29日 #

把自1970年1月1日以来的秒数转化成年月日

#include <iostream>
using namespace std;

bool IsRound(int year){
 if((year%100)&&(year%4==0)) return 1;
 if((year%100==0)&&(year%400==0)) return 1;
 return 0;
}
int main() {
 int n;
 int year_s[2]= {365*24*60*60, 366*24*60*60};
 int month_s[2][12]={{31,28,31,30,31,30,31,31,30,31,30,31},
   {31,29,31,30,31,30,31,31,30,31,30,31}};
 int day_s = 24*60*60;
 int hour_s = 60*60;
 int minute_s = 60;

 

 while(cin>>n){
    int temp = n;
    int year=1970;
         int month=1;
         int day=1;
         int hour=0;
         int minute=0;
         int second=0;

    while(temp>=60){

     int flag= IsRound(year);
     if(temp>=year_s[flag]) { year++; temp-=year_s[flag]; }
     else if(temp>=day_s){
      int days = temp/day_s;
      temp=temp%day_s;
      int i=0;
      int flag = IsRound(year);
      int hh=31;
      while(days>=hh){
       days-=month_s[flag][i++];
       hh=month_s[flag][i];
       }
      month+= i;
      day+=days;

     }else if(temp>=hour_s){
          hour=temp/hour_s;
          temp%=hour_s;
     }else if(temp>=minute_s){
           minute = temp/minute_s;
           temp%=minute_s;
     }
     }
     second = temp;

        cout<<year<<"-";
      if(month/10==0) cout<<"0";
      cout<<month<<"-";
      if(day/10==0) cout<<"0";
      cout<<day<<" ";
      if(hour/10==0) cout<<"0";
      cout<<hour<<":";
      if(minute/10==0) cout<<"0";
      cout<<minute<<":";
      if(second/10==0) cout<<"0";
      cout<<second<<endl;
 }


 return 0;
}

posted @ 2010-05-29 13:54 雪之精灵 阅读(1441) | 评论 (0)编辑 收藏

2009年6月20日 #

Don Knuth's Home Page

http://www-cs-faculty.stanford.edu/~knuth/

posted @ 2009-06-20 11:33 雪之精灵 阅读(84) | 评论 (0)编辑 收藏

2008年12月23日 #

思维的方法

         在这个网络时代,几乎任何知识性的问题都可以迅速搜索或请教到答案。不过,如何在已知知识之外发掘出未知知识,如何解决未知问题,那就还是要看个人的能力了,需要我们发挥自己的思维。
         用优秀的思维去解未知问题,这样可以成就大的学问。我们需要培养自己的思维。开始时,是有意识的去用这些思维方式;然后,发展到潜意识地去用这些方式,这就到一个境界了。 http://blog.csdn.net/pongba/archive/2008/12/18/3549560.aspx

          当然,我们还要先养成自己解知识性问题的基本功,并且要花大力气,下苦功夫。这是基础。

posted @ 2008-12-23 11:09 雪之精灵 阅读(135) | 评论 (0)编辑 收藏

2008年10月22日 #

DFS,BFS,DFS+ID

In a Nutshell Search Time Space When to use
    DFS O(c k) O(k) Must search tree anyway, know the level the answers are on, or you aren't looking for the shallowest number.
    BFS O(c d ) O(c d ) Know answers are very near top of tree, or want shallowest answer.
    DFS+ID O(c d) O(d) Want to do BFS, don't have enough space, and can spare the time.
d is the depth of the answer k is the depth searched d <= k Remember the ordering properties of each search. If the program needs to produce a list sorted shortest solution first (in terms of distance from the root node), use breadth first search or iterative deepening. For other orders, depth first search is the right strategy. If there isn't enough time to search the entire tree, use the algorithm that is more likely to find the answer. If the answer is expected to be in one of the rows of nodes closest to the root, use breadth first search or iterative deepening. Conversely, if the answer is expected to be in the leaves, use the simpler depth first search. Be sure to keep space constraints in mind. If memory is insufficient to maintain the queue for breadth first search but time is available, use iterative deepening.
    quote from http://ace.delos.com/usacotext2?a=y9SZdbB6WeB&S=rec

posted @ 2008-10-22 19:02 雪之精灵 阅读(438) | 评论 (0)编辑 收藏

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