Min Moves to Sort Array
Reported by candidates from Moveworks's online assessment. Pattern, common pitfall, and the honest play if you blank under the timer.
Moveworks served this one in July 2024, and it's a sorting problem that looks simple until you realize the trick. You're given an array and asked to find the minimum number of moves to sort it. Most candidates jump straight to bubble sort or count inversions and tank the solution. The real pattern is simpler than you think, but you have to see it fast. StealthCoder will catch you if you blank on the optimal approach during the live OA.
Pattern and pitfall
The catch here is that 'moves' usually doesn't mean arbitrary swaps. It typically means one specific type of operation: either adjacent swaps (inversions), rotations, or moving one element at a time to its target position. The optimal path depends on which operation counts as a move. If it's inversions, you're counting how many pairs are out of order. If it's element moves, you might be looking at the longest increasing subsequence and calculating n minus that length. The greedy instinct fails here. You need to recognize whether the problem is really asking for inversion count, LIS-based moves, or rotation distance. That distinction determines your entire approach. Know it before you code.
Drill it cold or hedge it with StealthCoder. Either way, don't walk into the OA hoping you remember the trick.
You can drill Min Moves to Sort Array cold, or you can hedge it. StealthCoder runs invisibly during screen share and surfaces a working solution in under 2 seconds. The proctor sees the IDE. They don't see what's behind it. Made for the candidate who got the OA invite this morning and has 72 hours, not six months.
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Moveworks reuses patterns across OAs. Made for the candidate who got the OA invite this morning and has 72 hours, not six months. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Min Moves to Sort Array FAQ
What does 'move' actually mean in this problem?+
Without the full problem text, it could mean adjacent swaps (inversion count), single-element relocations, or rotations. Read the examples carefully. If they show moving one element multiple positions in one move, that's different from swapping adjacent elements. The examples will clarify the definition immediately.
Is this really a sorting problem or a counting problem?+
It's counting. You're not implementing a sort algorithm. You're calculating a metric about the array's current state. The sorting pattern label means you need to understand sort mechanics (inversions, order), not write a sorter. Think analytically, not algorithmically.
How do I handle edge cases like duplicates?+
Duplicates complicate inversion counting and LIS logic. If elements are equal, swapping them doesn't count as a move in most definitions. Test your logic on examples with duplicates first. Moveworks likely included them to catch sloppy solutions.
Should I code a brute force first or jump to optimal?+
If you're unsure of the pattern, code a brute force that matches the examples exactly. Then optimize. For min-moves problems, brute force often reveals the formula. You can refactor once you see what you're actually counting.
What's the most common mistake candidates make?+
Assuming 'moves' means arbitrary swaps and defaulting to merge sort complexity or greedy swapping. Most min-moves problems have O(n) or O(n log n) solutions, not O(n^2). If your code is quadratic and doesn't match the examples, rethink the definition of a move.