SRM 599: Shame

Hello, sadly I'm not in a good mood. Yesterday night I took part in SRM 559, which gave me a (-37) score, a reasonable low score due to a 0 point final score (I didn't solved any problem).

The problem set was harder than usual, with a dynamic programming problem in 250 DIV 2. The problem statement isn't available online due a bug in Topcoder site, so, the problem asks the highest column possible built using blocks of positive heights(of course).

1) With their indexes in ascending order.
2) A block with even height can't be built up a block with odd height.

Clearly a dp problem, I used all the time I could for reach a simple state for the dp but I didn't did it. After a bad sleep night and a wake up against my desire, I gave another chance for this problem, and finally found an winning stated which passed in the system tests.

Think of an a dp[i] which, dp[i] stands for the maximum height for a column ending which block[i];

The base case for a dp[i] is b[i], making it:

$dp[i] = b[i]$
Iterating over the 0 to i blocks, we first check the existence condition number 2 and them check, the maximum ending with b[i] block is dp[j] (column with maximum height ending with b[j]) + b[i] (height of the actual last block) making our state passage being like this:
$ dp[i] = max(dp[i], dp[j] + b[i]) $

The final code is this:
Feel free to ask some doubt or show your thoughts in the comments, for an editorial of 500 HyperKnight problem, check out vexorian Link awesome tutorial.

Java 7 in Xubuntu 12.04

Hello, I'm here today to show to present the easiest way I've found to install both JRE and JDK version 1.7.xx in Xubuntu 12.04 (I think it works in all 'buntu' 12.04 versions). So, to start off, you have to add the following repository for your system:

sudo add-apt-repository ppa:webupd8team/java

Then, update all your repositories:

sudo apt-get update 

Kicking the installation off:

sudo apt-get install oracle-java7-installer

And finally, exporting $JAVA_HOME and $JDK_HOME to your $PATH environment variable:

export JAVA_HOME=/usr/lib/jvm/java-7-oracle
export JDK_HOME=/usr/lib/jvm/java-7-oracle/

Now, your latest version of Java 7 is up and running, to check if everything went alright, you should check:

java -version

and

javac -version

and see if they point out to the version you've just installed. So, hope it help you ;)