These files are for the book "Cracking the Coding Interview, 6th Edition," by Gayle Laakman McDowell.
Question 1.5 is interesting. The book's solution is erroneous. I was the first person to report an erratum in the 6th Edition on Ms. McDowell's website! I've included the book's solution, my solution, and my e-mail to Ms. McDowell.