Thanksgiving Vacation.

Mostly spent time at home relaxing. Original plan was to go for shopping on early morning. However due to stomach ache, had to stay in. Managed to visit a couple of electronics shops on Black Friday with mild stomach pain. Such was the power of discounts offers of Black Friday :)  As asked by Dan Ariely, why is it difficult to resist temptation for free (discount) stuffs? Why do cheapest stuffs sale so fast although the next expensive stuff is only a few dollars more?

Visited software section in different stores. I found that many software were FREE after mail-in rebate. For example, one could buy AVG anti-virus s/w (valid for 2ys) for $60 and they would get cash rebate within 8 weeks. I am wondering why people were not buying? Do we value $60 and its depreciation so much that we hesitate to keep it in someone else's pocket for two months?

Books Read/Reading in 2009.

1. 401(k) for Dummies
2. Predictably Irrational
3. Outliers: The Story of Success
4. White Tiger
5. Kite Runner (reading)
6. Super-Capitalism (reading)
7. Effective C++ (reading)
8. Code Complete (reading)

Rab Ne Bana Di Jodi

Haven't watched the movie but from the review it seems many people like me can identify with Mr Suri (SRK character). The songs are awesome -- quite relevant and meaningful and were sung by good singers -- Sukhwinder, Sonu, Shreya, Sunidhi, Roopkumar etc. 

The song "Phir Milenge Chalte Chalte" is so funny in that an amateur singer often mixes up different songs and their tunes. What an observation from the composer !  

"Dance pe Chance" is a song on how to teach dance steps to a novice. I can really identify as I had the same experience in my dance classes. The instructor would break it down into basic steps.  

Convergia Rip-Off

Yes, there are still scam and fraud businesses in US and can rip one off blatantly. Convergia is a Canada based company and has agents in India and elsewhere. I kept getting annoying calls from agents probably located in India. They would call me periodically and used to offer a great deals for calling to India. Convergia agent told me that the deal would be flat rate of $60 dollars and unlimited calls to any numbers in India from US. The first month would be free for trial. They gave me a code and asked the local carrier such as AT&T to add that code. They told me there was no paper contract and I could disconnect anytime. I could pay the bills using check or card card.

The deal sounded quite reasonable and I subscribed to it. After using for 3 days, I could not make any further calls to India. After trying for many times and waiting for long long hours, I got hold of the customer care agent. She told me my account was blocked by the computer due to over-usage. But there was no mentioning of it in the contract. Actually there was no contract (my mistake that I didn't have the proof). I immediately cancelled my subscription on phone. After a month, I got a bill of $111. They mentioned that I was charged for all the calls. Wait a minute, I was told the first month was free. It seems they didn't cancel my account. I didn't send the bill. In the second month, they send another bill of $222. I sent a check of $111 and wrote on the check "my account should be canceled as soon as this check is encashed". Now, I have a proof of cancellation. But I am still trying to resolve $111 that was charged in the second month although I made no calls.

Garmin GPS

I have been using GPS navigation devices for sometime. I was told Garmin was the best brand for GPS. It's hard to judge how good a brand could be unless one uses some other variety. So, last week, I rented a Hertz car in which they had already installed a GPS which was custom made. I would say, the GPS only helped me find a route between a source and a destination. The interface was not friendly at all - it was not a touch screen and the keypad prompted every key I pressed a key. Pressing the letters and numbers was inconvenient. Morevoer, there was no option to search for businesses close to a place. It happened that I pulled over the car and searched for the Starbucks cafe. However, it returned all addresses in different states and cities. I realized that I was standing next to a Starbucks cafe and the GPS failed to locate it. What a performance !

It is obvious that the Garmin GPS is indeed among the best. First of all, the vendors underestimate the value of simplicity and user-friendly (Google-like interface). The interface needs to be touch screen. It's a pain to punch in keys. Today I was traveling from LA to Riverside and the traffic on the freeway was extremely bad. However, the Garmin GPS kept finding alternative routes for me. The GPS takes into consideration an existing congestion in the freeway. For example, at one point of time, it told me to take an exit and re-enter the same freeway from the right side (it was awesome that I could cut through the traffic for 1/2 mile several times). It does many other optimization to save time. Another feature that I like in Garmin GPS is the option to localize near by attractions, restaurants etc.

Interesting thing is that all the GPS devices have the same broadcasted information from a satellite, still there is so much difference in performance.

More Interview Questions:
As I went through more interviews, I was asked some interesting questions. If you happen to know the solutions or want to know the solutions, you write to me.

[1] Given an array of n integers both positive and negative integers. Find the sub-sequence of the array which has the largest sum. Find the algorithm with a better complexity than brute force one.

[2] Given a character array, print all the palindromes. Find an efficient algorithm.

[3] Write a C program to show if stack is growing into higher memory.

[4] How to make a server accept client connections in a non-blocking mode efficiently ?

[5] Find the Kth largest element in a binary search tree.

[6] Many more to come ...

Good Interview Questions


Sometimes I wonder what is the purpose of asking problem solving questions in an interview ? Some of the interesting questions I came across in the recent past are as follows. I have solutions to some. Do let me know if you have an effiicient solution.

1) Given an array of integers randomly selected from [1,n], what is the average number of comparison to be made in finding the minimum integer ?

2) What is the complexity of merging two lists of numbers ? How will you improve the complexity if one list is very large compared to other ? What if the numbers are distributed uniformly in [1,n] in both the lists ?

3) Given a circular list of integers (some of which could be -ve), find an index i such that sum of integers from index i to index j is never < 0. First find out if such an i exists.

4) Given n sets and each set consists of characters. Let the sets be S1, S2, S3, .., Sn. Given a string denoted by x1..xk. Find out if the string x1..xk can be constructed from S1, S2, ..., Sn by first looking at S1 and then S2 and finally Sn in an efficient manner. You can look at any set only once and you need to follow the ordering for looking at the sets. In one case, assume that you can skip a set. In another case, assume that no set can be skipped.