Straight from the book… A binary tree is a hierarchical structure of nodes, each node referencing at most to two child nodes. Every binary tree has a root from which the first two child nodes originate. If a node has no children, then such nodes are usually termed leaves, and mark the extent of the tree structure. A particular kind of binary tree, called the binary search tree, is very useful for storing data for rapid access, storage, and deletion. Data in a binary search tree is stored in tree nodes, and must have associated with them an ordinal value or key; these keys are used to structure the tree such that the value of a left child node is less than that of the parent node, and the value of a right child node is greater than that of the parent node. So with that, let’s dive into the code.

There are two ways you can find a key in a binary tree, recursively and iteration with a while loop. Since most places allow you to do pseudocode, I’ll keep my answers short and sweet.

Recursion

Node Search(Node, key)
{
    if Node = NIL or key = Node.key
        return Node
    if key < Node.key
        then return Search(Node.Left, key)
        else return Search(Node.Right, key)
}

While Loop

Node Search(key)
{
    Node = root
    while Node != NIL and key != Node.key
        do if key < Node.key
            then Node = Node.Left
            else Node = Node.Right
    return Node
}

I’ve realized after going through a few of these interviews that if you solve a problem using an iterative function, they’ll most likely ask you to solve it using recursion as well, so make sure you understand the basics of recursion. Thanks for reading this post. I hope it proves useful to you in your job hunt.

-DeVaris

First up is the classic reverse a string problem. I think I got asked this at least 6 times during interviews. It’s like a warm-up to coding question, but you’d be amazed at how many people fumble on this exercise.

The first method I’m going to use is the easiest to remember/implement:

public static string Reverse( string text )
{
    char[] charArray = text.ToCharArray();
    Array.Reverse( charArray );
    return new string( charArray );
}

The method takes a string as a parameter, copies the string to a char array using the ToCharArray() instance method, reverses the characters in the array using the Reverse() instance method, then returns the reversed char array. Pretty simple right?

There are always more than one way to solve a problem so I’m going to show you some other implementations of methods that reverse strings.

Reading from end of string

public string Reverse(string text)
{
    string reverse;
    for (int i = text.Length - 1; i > -1; i--)
    {
        reverse += text[i];
    }
    return reverse;
}

Reverse using stack (Push and Pop)

public static string StackReverse(string text)
{
    Stack<char> revStack = new Stack<char>();
    foreach (char c in input)
    {
        revStack.Push(c);
    }

    StringBuilder sb = new StringBuilder();
    while (revStack.Count > 0)
    {
        sb.Append(revStack.Pop());
    }

    return sb.ToString();
}

Hopefully, now when you encounter this problem in an interview you won’t have any issues solving this problem with confidence. Until next time…

-DPB

When I look at my peers at Microsoft, I see a vastly diverse group of individuals with one commonality amongst them: PASSION. Not all of them graduated from top engineering schools like University of Illinois Urbana Champaign (FULL DISCLOSURE: I’m an alum haha I-L-L…I-N-I) with 4.0 GPAs, but they are THE BEST in their respective domains. Not only are they technically proficient, they also embody their passion. They know the history, various areas of application, new developments and key figures of their domain. As a student, you can display this passion in a number of ways.

Classroom Excellence – You have to show that you can at least do your class work for your intended career path. I was always horrible at the objective courses like English, Psychology, History, etc… but in Math and CS I excelled. If you don’t get the basics, you won’t do well with the application. You have to have a solid foundation in order to succeed in anything that you do. The lowest hanging fruit is doing well in class. If you say you are programmer but don’t know how to simply reverse a string, then there’s a problem.

Projects/Research – Another commonality I observed is that most of the people did some amazing project outside of what was required for class. Whether it was with a club like ACM or as a research assistant, they completed a project and can talk at length about the intimate details of the project. This comes in handy when the interview question “Can you tell me about a project that you’ve participated in” comes up. Participating in student research competitions is a great way to get exposure for your project within the technical community and you can talk about the experience for years to come. If that’s not your speed, then do community based projects. Your local high school may need a database or the church may need a website. Showing application of your knowledge outside of the classroom is an excellent way of demonstrating passion for your craft.

Stay Visible – If you want a job at Microsoft you have to make sure that we know as well. Recruiters and other representatives should know who you are by name and can recall at least one of your accomplishments. I can recall of an instance where a student didn’t have a stellar GPA but was super involved on campus and attended every Microsoft event. They eventually got an internship as a PM because of their presence and participation at our campus events. If we haven’t visited your campus in a while, there are ways to still be visible. You can visit your local .NET User Group meeting. These are usually attended by a field employee and will give you visibility into how .NET is used in your local region. You can apply to be a student partner and become our campus liaison. You can attend local, regional and national conferences, and we 99.99999% of the time have an academic discount. You can also participate in our student competition, the Imagine Cup. While this list isn’t exhaustive, these are typical ways of gaining visibility from Microsoft.

I know passion is an emotion that’s sometimes hard to quantify, but in the technical realm if you follow these steps you will set yourself up for success in the long run. I hope this helps all that have wanted to get a job at a top company like Microsoft. If you have any questions, please feel free to contact me at debrown@microsoft.com

Don’t Say No

I know a lot of people are wondering why I’m saying this because it’s probably the opposite of what you’ve been taught but trust me there’s a benefit to this. In school, there will be a plethora of opportunities, foreign and familiar. These experiences will undoubtedly shape the rest of your life. If you haven’t seen the movie “Slumdog Millionaire” I highly recommend it because it epitomizes this message. The main character goes on the Indian version of “Who Wants to be a Millionaire” and gets accused of cheating because he was from the slums and couldn’t possibly get all the questions right. The movie goes on to show how his experiences allowed him to get enough knowledge to answer the questions and ultimately win the grand prize.

Join clubs, study abroad, make new friends, take quirky classes and seminars, and take road trips. I’ve learned that success from opportunities is created when you’ve exposed yourself to a broad range of things. In my life, I’ve been successful in part because of my ability to relate to people on a multitude of levels. One quote that sticks with me is from Mark Twain “Don’t let schoolin’ get in the way of your education.” Don’t be afraid…Try it because you just may like it.

Maintain Your Reputation

On the flipside of your exploration, you have to remember to always maintain your reputation. Assume that in your lifetime that you are going to run for president and everything you’ve done will be dissected with the precision of a surgeon, will you be confident they won’t find anything incriminating? We live in a different time where access to information is instant and ubiquitious. So before you go out drinking and partyings with your friends, think about the outcomes of your decisions. Before you post pictures on Facebook, Myspace, Twitter, etc… think about your employer seeing them or your family. If granny can’t take them pictures to church or your parents can’t talk about what you did last weekend with reverence, it’s probably not a good idea to partake. Remember, reputations are like glass. Once broken, they are near impossible to fix.

Find and Cultivate Your Passion

Schools are an excellent place to find and cultivate your passion. There are so many things you can expose yourself to and on top of that receive in depth training from people more experienced than you in your field. Taking classes, talking with professors, joining clubs/organizations, going to seminars and conferences are all excellent ways to cultivate your passion. Having others around you with similar interests will go a long way because it’s always good to get different perspectives on your ideas.

Once you find it it’s time to apply it. You have to become a domain expert and embody your passion. Know the history, the future, and the intimate details. Drill yourself on the fundamentals of your domain. Read articles and books. Get involved in the community. Experiment and try to apply your passion in non traditional ways. You’d be surprised at what you come up with and it may even lead you down a path more tailored to your lifestyle and interests.

Prepare For Life After College

From the moment you step onto campus, you should already be making steps for a career after college. The first big decision you have to make is what major/minor is going to keep your interest for the next 3+ years. Never ever major in something just because they have great starting salaries or there’s some prestige associated with it. You’ll waste time taking classes you don’t need and a 4 year experience will easily turn into 5+. I always suggest doing subjects that complement each other. For instance, I was interested in Computer Science but always knew I wanted to own my own business so I minored in Business Administration. Employers also want to see interest in your major outside of the classroom. I recommend doing research, joining professional organizations, and participating in contests. Taking internships is also contributes to your success after college. Not only are they a good foot in the door, they also expound upon the theory you learn in school with some practical industry knowledge.

I hope this post regardless if you’re in school or on the job can inspire you to make the most out of this life you’re given. And if you have a younger sibling or know someone getting ready to make the journey to college, show them this post. Talk about the things that I’ve presented. If you have any questions, feel free to email me at debrown@microsoft.com.

Over the coming days, weeks, months, and years, I will showcase different technologies, bring up topics to inspire conversations, and give a peek into my life as I travel around the country evangelizing technology. Stay tuned and I guarantee you’ll be entertained and inspired.