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These are my revision notes for my job interviews. As a contractor, I have job interviews more often than a permanent employee. Writing down the revision notes does not imply that I am incapable of answering these questions naturally. During interviews, I naturally get nervous, and due to my introversion, I often struggle to clearly articulate what I already know and understand. I simply want to avoid those situations and prepare myself to present myself in the best possible way.

What is big O?

  • Mathematical notation

  • Describe the time complexity or space complexity of an algorithm.

  • Time complexity of O(n) will have its execution time grow linearly as the input size increases.

  • Time complexity is O(1), the algorithm executes in constant time, regardless of input size.

  • O(n²) means the time taken will be proportional to the square of the size of input, and so on.

What is recurrence?

In the context of computer science and algorithm analysis, recurrence is a way of defining a problem in terms of one or more smaller instances of the same problem.

A good example of this is the Fibonacci sequence, where each number is the sum of the two preceding ones. In terms of a recurrence relation, it could be defined as:

F(n) = F(n-1) + F(n-2)

with base cases:

F(0) = 0, F(1) = 1