Know your data structures, algorithms, design patterns and test case uses for any technical job interview!!
This might not be quant related but if you are applying for any development type roles (name me a quant based position that is not), ensure you know the notes below.
Let me stress this (once again right), know these topics really well. I have done at least seven interviews which involve one hundred percent rate of design patterns. I was kind of dumbfounded on the level of detail interviewers go into on this. There are some great resources out there but it might be wise to pick up a copy of Gang of Four in Design Patterns. This seems to be to the bible in this arena. They also started the concept of this.
We were all taught data structures in our early years of computer science courses. You need to know these areas well too. Understood the logic and reasoning of why these data structures are used. Focus on the basic ones including stack, heap, singly and double linked list, binary search tree, and even graphs. Also understand the concept of the Big O algorithms which involved time and space complexity. A great site to learn this from is algolist.net. It has some great tutorials to have you understand this data structures with code snippets in both Java and C++.
Let’s get into the less talked about algorithms. Depending on the type of company you are applying to, I would recommend to learn the basics including Fibonacci, prime, factorial, and all the basic sorting algorithms. These include your typical sorting like bubble, selection, insertion, merge, and quick sort. Again know the time complexity of each sorting algorithm. A good explanation of this is found at Wikipedia.
Regardless of what level of position you are applying, be expected to answer questions on these above concepts. You should consider emphasizing your knowledge in design patterns if you are going for a senior role or even architect level.