507. Find the Library Book Row

A librarian has organized books in a long row where each book has a unique identification number. The books are sorted in strictly increasing order. Given an array of book IDs books and a target ID, return the index of the book if it exists. If the book is not in the row, return -1. You must implement an algorithm with O(log n) runtime complexity.

Example:
Input: books = [10, 20, 30, 40, 50], target = 30
Output: 2

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