What was the hardest part of writing Harry Potter and the Philosopher's Stone?

Answer 1

J.K. Rowling herself is the only person who knows the answer to this.

From interviews, we know that getting the book published was a difficult task. Every major publisher rejected Harry Potter and the Philosopher's Stone before Bloomsbury decided to give it a go. It took Rowling two years to get the book published.

We also know that she wrote, and rewrote much of the book - sometimes whole chapters were rewritten at a time. The first book took five years to complete although it should be noted that during this time Rowling was also outlining the rest of the series and that there is a lot of material that never made it into the books.