LeetCode #26 — Remove Duplicates from Sorted Array: How to Actually Think About It

Day 1, Problem 3 of LeetCode's Top Interview 150. The headline lesson of this episode: **problem qualifiers like "sorted" aren't decoration. They're optimization unlocks.** This problem reuses the slow/fast two-pointer scaffold from #27 Remove Element with one tiny change in the filter rule — but the *real* lesson is *why* that change works, and that lesson generalizes to dozens of other problems. By the end of this episode you should be able to answer: (1) what does the word "sorted" actually give you? (2) why don't you need a hashset for this problem, even though it's a deduplication problem? (3) how is this the same algorithm as Remove Element, with only the filter rule swapped? ## What we're doing here You're given an integer array `nums` sorted in non-decreasing order. Remove the d...