I came to their offices in Haifa. The architect who interviewed me explained the company to me, asked me to tell them about myself, gave me a page with four questions, and then asked another one.

Given a number, n, decide if n is a power of 2.

Afterwards, he asked me about the complexity of the solution and if I would rather keep (Hash, List, etc.) all the numbers that are powers of 2 (32 ints) instead of performing the calculation.

Implement a thread-safe Singleton.

Given an array, return the 2nd biggest number in one run.

Part 2: How would you design an LRU cache? This was a discussion about the advantages and disadvantages of each approach.

Implement the LRU discussed above.