First of all, you need to pass a personality test, which is similar to the SAT. I think it is quite easy, but one of my friends just failed. After that, some hiring staff will call you and ask routine questions. For example, how many hours did you spend on programming each week and what's your GRE or GPA grade. Then I went to a local library to take a skill test. The first part is logical questions about their internally used syntax/language, which is not difficult. The second part has four programming questions. All of them are string operations. You can use any language you feel comfortable with.

Get all well-ordered substrings from a series of numbers. A well-ordered substring is a string composed of ascending numbers.