A coding interview usually takes 30 min, 45 min or 60 min. You need to solve the problem by writing code either on the white board or using a online collaborative editor.
What will be covered
Coding interview questions primarily focus on data structures and algorithms.
You should be familiar with the basic data structures, like array, linked list, stack, queue, tree, graph, etc.
How to practice
There are many online judges to help you practice, like LeetCode, LintCode, Hackerrank, etc. Now there are thousands of problems on those websites, and it is almost impossible (and actually unnecessary) to finish all of them.
We have solutions to some of the most popular problems on this site. You can find the full list of problems and solutions (sorted alphabetically) on the Problems page. If that is too overwhelming, below are some problems categorized by types.