---

$100 Laptops

"The MIT Media Lab has launched a new research initiative to develop a $100 laptop-- a technology that could revolutionize how we educate the world's children. One Laptop Per Child (OLPC) was announced by Nicholas Negroponte, Lab chairman and co-founder, at the World Economic Forum at Davos, Switzerland in January 2005."

Read more on this at <http://laptop.media.mit.edu/>.

Love ko to

Thank God for McDonalds.  With my present job as a programmer, I find myself waking in odd hours because my body clock is already used to it.  Because I don't know how to cook my own meal, I have to rely on restaurants and cafeterias to supply my body with much-needed energy.  The restaurants are already closed at this hour, so I had to sacrifice my hard-earned money just to eat.  McDo is kindda expensive.  I spend more than a hundred bucks, and I'm still not satisfied.  The McDo crowd is different in the evening.  I find myself surrounded by Med and Law students who are burning the midnight candle.  Anyway, I'll just eat to my heart's content tommorrow.

Ten-digit Perfect Square Numbers

In one of the mailing lists that I've subscribed to, a question was posed yesterday for finding a ten-digit number consisting of distinct digits that is a perfect square. Wikipedia defines a perfect square as "a positive integer which is the square of some other integer, i.e. can be written in the form n^2 for some integer n."

I wanted to code my solution using C/C++, but not all of us have compilers.  Thus, I coded my solution using JavaScript.  To see the results, just copy and paste the code below and save it to a file with .html as its filename extension.  Then, run it in your browser.


Some of the Answers
   1026753849 (lowest value)
   9814072356 (highest value)

There are 87 possible answers.


Solution
<script type="text/javascript">
function isUnique(n) {
    var str = new String(n);
    var tmp = new Array(10);
   
    for(var i = 0; i < 10; i++) {
        tmp[i] = null;
    }

    for(var i = 0; i < 10; i++) {
        if(tmp[str.charAt(i)] == null) {
            tmp[str.charAt(i)] = str.charAt(i);
        } else {
            return false;
        }
    }
 
    return true;
}

function main() {
    var lbound = 31992;
    var ubound = 99380;
    var count = 0;
   
    for(var i = lbound; i <= ubound; i++) {
        if(isUnique(i * i)) {
            document.write((i * i) + "<br />");
            count++;
        }
    }

    document.write("There are " + count + " possible answers.");
}

main();
</script>


Discussion 
The lowest possible solution is 1023456789, and the highest possible solution is 9876543210.  Although 0123456789 is the lowest possible number that can be constructed using 10 distinct digits, I leave you to find out why we can't use it as a lower bound (duh). :)

The square root of 1023456789 is aprox. 31991.51.  We round it off to 31992, and start finding the solution here.  The square root of 9876543210 is aprox. 99380.80.  We round it off to 99381, and stop finding the solution here.  The script then calculates the square of every number from 31992 to 99381, and displays it if the result consists of distinct digits.

Dreams

It's been years since I've last remembered my dreams.  I don't know why, but it seems that I have lost my ability to recall them as I grew older.  When I was a 3-year old kid, I often had this dream, which seems very real, about wandering around our neighborhood accompanied by my guardian spirits (I sometimes see Satan, but he can't hurt me nor can my guardian spirits hurt him).  Today, I'll try to bring back that "skill" because I could just imagine the many possibilities I can do in my dreams.  I'm no longer a 3-year old kid, so my motivations *ehem* are no longer innocent. Hehe.

Coldfusion's isNumeric(): A different approach

My friend, Aldwin, has a different approach in solving the isNumeric() problem mentioned in my previous post.  Here is his solution for the module that he's working on (I've slightly modified it to remove sensitive information):

Please note that this is only applicable for certain (preferrably pre-validated) inputs.  This will not flag an error for inputs such as "8.-.16-" or "...32.256"

Work-around for Coldfusion's isNumeric() function

Problem:  You need to determine whether a given input is a number or not.  Unfortunately, Coldfusion's isNumeric() function only checks whether a number can be treated as a number internally.  Therefore, the following strings (without the quotation marks) would cause the function to return a true value:

Although this is fine for many applications, this is often not the desired behaviour such as when you need to validate them before passing it to a MySQL query.

Solution:  A solution I've found so far is to use Regular Expressions.  We use REFind to search for the following regex pattern:


Example:


Please note that this is also applicable to other programming languages that support Regular Expressions (i.e.: either built-in or through a library), although this may no longer be necessary for more elegant languages such as PHP (sorry, I'm biased).

Generating RTF

I'm making a web-based payroll system right now.  Since we need to generate print-outs of the data, I opted to format it using Microsoft's proprietary (?!) Rich Text Format (RTF).  I didn't choose PDF because it's a bit complicated, and because we are on a tight deadline (was it a correct decision?).  I have no formal training on this whatsoever, so I had to rely on samples to deduce some of the rules that make up this document language.

The text that MSWord generates is so horrible.  I had to examine lengthy sequences such as this:

This is fun! :)

The Tao of Programming

When I was a kid, I used to find The Tao of Programming rather boring and confusing.  Now that I'm older (but still a kid, nevertheless), I now find it very funny because I can now relate.

Read more about the Tao of Programming here.

Wala Lang

Yikes.  This blog is supposed to be a venue where I can discuss problems, solutions, and ideas relating to Computer Science and Information and Communication Technology.  I don't know why I can't bring myself into the mood for serious thinking right now.  I've been waiting for it to come, but it seems that I can only sustain my concentration for a couple of hours each day.

Anyway, this post shall mark the end of my posting inane remarks in this blog.

deleted

*poof*  This entry is now null and void.

Next page >>