Test your knowledge: Python Binary Search with bisect

Review

1. For values = [10, 20, 20, 40], what do bisect_left(values, 20) and bisect_right(values, 20) return?

   The duplicate values occupy indexes 1 and 2, so the left boundary is 1 and the right boundary is 3.
2. Why does bisect_left(values, target) not by itself prove that target is present?

   Bisect computes an insertion boundary. An absent value can still have a valid insertion index.
3. Which pattern safely tests for an exact match after bisect_left(values, target)?

   Bounds must be checked before indexing, and a candidate at that index must also equal the target.
4. What does insort(values, item) do when values is already sorted?

   insort combines the boundary search with list insertion; it mutates the list.
5. When calling bisect_left(records, 7, key=record_score), what should 7 represent?

   The target x is already the comparison key. insort differs because it applies key to the new item during its search step.
6. What is the main performance limitation of insort on a Python list?

   The search is logarithmic, but list insertion moves later elements and therefore takes linear time in general.