Retrieval: the four habits

Two problems rebuilt cold, plus the checklist that prevents most linked list bugs.

Quick check· 5 min

Diagnose the symptom

You split a list into halves, reverse the second half, and interleave them. The program hangs forever. What is the most likely cause?

The split did not set the first half's last next to None, so the halves are still connected and the reversal created a cycleThe fast pointer moved three steps at a time instead of twoA dummy head was not used before the interleaveNode comparison used == instead of is

Problem· 20 min

Reorder List, from scratch

You have solved this one before. Rebuild it from scratch without looking at your old submission. If the approach does not come back within a few minutes, that is the signal that it needs another pass.

Problem· 18 min

Meeting Rooms II, from scratch

Linked Lists

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Linked ListsLesson 12 of 12About 48 min