The bisect Module: Stop Reinventing the Wheel

Concepts: pyBisect, pyBisectLeft, pyBisectRight

Python ships with a battle-tested binary search module in the standard library. In production code and in many interview contexts, bisect is the correct tool. Knowing when to reach for bisect instead of writing your own is a senior engineering signal. It says: 'I know the standard library, I do not write code I do not need to write, and I know what problems require custom logic versus solved problems.' bisect_left vs bisect_right The critical difference is how equal elements are handled. bisect_left returns the leftmost position where target could be inserted to keep the array sorted. If target is already present, this is the index of the existing element. bisect_right returns the rightmost position, i.e., just after all existing copies of target. When to Use bisect vs Roll Your Own