Use Minimum Tokens
Reported by candidates from Amazon's online assessment. Pattern, common pitfall, and the honest play if you blank under the timer.
Amazon's 'Use Minimum Tokens' problem showed up in April 2025 and it's a greedy classic with a graph twist. You're given a set of tokens and some kind of exchange or traversal rule, and you need to minimize the token count to reach a goal state. The trick is almost always ordering, so sort first and then decide your path. If you blank on the exact greedy choice during the OA, StealthCoder will read the problem onscreen and surface the right ordering instantly.
Pattern and pitfall
The core pattern here is greedy with a secondary structure, likely a graph or a state-space search. The problem usually involves trading off token costs: burn the cheapest tokens to unlock expensive ones, or vice versa. You'll sort tokens by cost or value, then simulate the process. The common pitfall is not considering both directions (e.g., buying vs. selling, or forward vs. backward traversal). Build your solution assuming you'll sort once and then iterate through a priority or sequence. StealthCoder acts as your safety net if you get stuck on the state transitions during the actual OA.
Drill it cold or hedge it with StealthCoder. Either way, don't walk into the OA hoping you remember the trick.
You can drill Use Minimum Tokens 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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Use Minimum Tokens FAQ
Is this a sorting problem or a graph problem?+
Both. Sort the tokens first to establish an order, then simulate traversal or state changes greedily. The graph part is implicit in how you move between states. Get the sort right and the rest falls out.
What's the trick with 'minimum tokens'?+
Always consider bidirectional trades. You burn cheap tokens to gain expensive ones, or vice versa. The greedy choice is often to trade in a way that maximizes your state or minimizes cost. Think of it as a two-pointer sweep after sorting.
How do I prepare in 48 hours?+
Understand two-pointer and greedy patterns. Practice a few LeetCode token or coin problems. The Amazon version likely has a state twist, but the sorting and simulation fundamentals are the same. You don't need deep prep, just muscle memory.
Will I need to handle edge cases like zero tokens?+
Very likely. Check for empty input, single token, and boundary conditions where no trades are possible. Amazon OAs often test these. Write them explicitly in your code, not as afterthoughts.
Is this problem still asked at Amazon in 2025?+
Yes, the April 2025 report confirms it. Token and exchange problems are stable in Amazon's rotation. The pattern doesn't change much, so focus on clarity and correctness over fancy optimizations.