I applied through a career fair and received an email within a week. I scheduled a technical phone interview for the following week. It was a 45-minute interview. The interviewer was nice, but I was not in good condition (I had just taken a nap, and my brain was not functioning well). We went straight to the problem. The problem was some dynamic programming stuff. I was afraid that I couldn't come up with the right solution, so I just started writing a recursive solution to save some time, and then we spent some time fixing it. I eventually came up with the "right" solution at the end, but I didn't have time to write it, so I just explained how it should work. Then, I asked a few questions, and that was it. I received a rejection email only 15 minutes later.

For encoding where {a, b, c, ..., z} maps to {1, 2, 3, ..., 26}.

If given a list of digits, for example, [1, 2, 3], this may represent:

• {1, 2, 3} -> {a, b, c}
• {12, 3} -> {l, c}
• {1, 23} -> {a, w}

Therefore, there are 3 possible interpretations for the list [1, 2, 3].

So, given a list of digits, calculate the number of possible interpretations for the list.