ACM programming problems

ACM programming problems archive:

http://www.ntnu.edu.tw/acm/ProblemSetArchive.html

Overflow in Binary search

Overflow in Binary search:
http://googleresearch.blogspot.com/2006/06/extra-extra-read-all-about-it-nearly.html

Apparently this bug was there in Java libraries till JDK 6.0

How to increase sudo timeout in linux

If you are tired of typing sudo too many times:
http://www.go2linux.org/disable-cache-password-sudo

Same procedure for disabling can be used for increasing as well. Just add a line to /etc/sudoers file through visudo

Defaults:userName timestamp_timeout = 20

Tomcat and default welcome page

I was trying to setup a quick website in my machine and installed tomcat and invoked it from browser as http://hostname it wasn't serving anything. Then I realised I had to add this block in web.xml

   index.html
   index.htm
   index.jsp

browser I added it and added an index.html and it still didn't work. Then I looked at webapps folder and saw a folder ROOT and added index.html there and it started serving home page!

Screen, bash and ctrl+a

Today I was using bash and ctrl+a is very useful for going to the start of a command in bash. But it was not working in my Mac. I thouht it was a problem in Mac bindings and opened keyboard and mouse, terminal preferences etc.
When none of this could fix the issue, I realised that I was ssh'ing to my work machine and using a screen to avoid losing session when connection drops. This program uses ctrl+a as the meta key and was not passing this on to bash. So I had to use
screen -e ^xx

to change the meta key to ctrl+x and everything was fine again.

Java 1.6 on Mac

See here:
http://dhruba.name/2008/12/22/compiling-java-16-projects-using-maven-on-mac-os-x/
http://answers.yahoo.com/question/index?qid=20090415211021AAFgnYh

one complement and twos complement in google search

It is really cool!

I was searching for 2s complement of -1 [I know how to calculate it. just to be sure!] . I just typed -1 in twos complement and it actually gave

-1 = 0xFFFFFFFF

very nice!

I searched for ones complement of -1 as well and it worked. Good work!