Classic Binary Search: Three Templates

Concepts: pyBinarySearch, pyBinarySearchTemplates

Here is the dirty secret of binary search interviews: most candidates know the idea but butcher the implementation because they do not have a clean template committed to muscle memory. The off-by-one errors at the boundary conditions are where people fail. You are going to learn three templates and understand exactly when to use each one. Pick one as your default and reach for the others when the problem demands it. Template 1: left <= right (The Standard) This is the most intuitive template. The loop runs while left and right have not crossed. When they cross, every index has been considered. Use this when you are looking for an exact match and want to return -1 if the target is not found. Template 2: left < right (Find the Boundary) Use this when the answer is a boundary position, not an