Why study data structures and algorithms?

- [Instructor] Let's understand why do we need to learn data structures and algorithms as programmers? When we solve programming problems, we would like to know, at least at a high level, how much time will that algorithm take to solve the problem. Does it take a few milliseconds, a few minutes, or a few days? Because having an estimate of time can help you decide how to break down your problem in relevant pieces or smaller problems. It will also help us decide on hardware requirements for solving a problem.

For example, if you know that executing or running an algorithm on a certain CPU takes, say, over an hour, we can use a more powerful CPU to reduce the time to a few minutes. Or we can think of breaking the problem and distributing it to many smaller CPUs, so they can execute a smaller problem faster and we can get our results in a few minutes. Understanding algorithms also help us know if a particular algorithm is feasible as opposed to it being impossible to do the job.

For example, if you are asked to solve a billion items based on some criteria in say, one second, you would like to know if it is even possible to do it at all. And of course, improvement is a never ending process. We would like to improve our existing algorithms, just like car manufacturers constantly work to raise the bar and want to make faster cars, even though it will seem like, well, what is the need, and that's probably how human interaction grows.

We keep improving. We want to keep improving. Now data structures are studied in context of algorithms. Data structures in computers are ways in which we store data. If we just store the data without doing anything with it, well, it doesn't really mean much, but particular ways of storing the data may help in faster access or faster saving of the data. For example, think about this.

In a library, what will be easier to lead us to a book? If they are kept like they are, in the racks, or if they are put up as huge piles? What if you find your book at the bottom of the pile? Will it be easy to take it out? Or even within the racks, if the books are kept in some order, or they are kept completely randomly, so the way we choose to keep the books, we make it easy finding a book, or easy keeping a book back in its place. In the same way, different types of data structures are used which will make sorting of items faster, or finding an item faster and so on.

So we choose a particular data structure in our program depending on which of the operation is more frequently used, or which operation we would like to be faster than the others.