First, they asked me to complete an online test on Hackerrank.com. There were 16 test cases, and I passed 15 of them. I tried many times but could not pass the last test case. After a couple of days, they emailed me to schedule a phone interview. A few hours after the phone interview, they emailed me to arrange the onsite interview.

In the phone interview, they asked about structure packing, signals, GDB, soft/hard links, inodes, and so on. The questions were not difficult, but I failed to answer some of them.

The onsite interview was 1:1 with two interviewers. The first was a technical interview. He asked:

• Implement a power of 10 template without runtime overhead.
• How to check if a class has a member function. (Failed to answer)
• Write the syntax to specialize the template function of a template class. (Failed to answer)
• Explain the implementation of virtual functions.
• Given the root of a binary tree and a value, find two nodes in the tree whose sum equals the value. (I wrote code with O(n log n) complexity.)
• Explain how mmap works. (I thought the OS mapped the region in the heap; instead, it mapped between the heap and the stack.)
• How to compute the size of the L1/L2 cache of a CPU without reading /proc/cpuinfo. (Failed to answer)

The second interviewer asked me why I chose the company, a little about my last project, etc.

After the onsite interview, I was rejected. Fair enough, as I failed to answer some questions.