For the second problem, I had an idea for a different hash function. Basically map each letter to a prime number (e.g. c = 5, d = 7) and then multiply the values in a word together. I guess depending on the length of the words it might overflow. But I thought it was interesting.
I gave this very solution in Google interview many years ago. It does assume that the input characters are of a limited set, e.g. English alphabet. The interviewer said they hadn't heard that answer before. It wasn't what they were expecting and took them a while to be satisfied it would work. I was offered the job but didn't end up taking it.
