Minimize Total Input Cost
Reported by candidates from Salesforce's online assessment. Pattern, common pitfall, and the honest play if you blank under the timer.
Salesforce hit you with this in November 2024, and it's a cost-optimization problem dressed up as an algorithm question. You're minimizing something across inputs or resources, which means you need to find the pattern that lets you skip the expensive paths. The trick is figuring out what "cost" actually means in context and whether greedy picking works or you need dynamic programming. StealthCoder can help you recognize the structure in real time if you freeze on the exact formulation.
Pattern and pitfall
This problem is testing whether you default to greedy or think in terms of state-space optimization. Most candidates try to pick the minimum cost input at each step and fail on cases where a slightly higher cost now saves way more later. The pattern usually breaks down into: identify what the cost function is (per-item, cumulative, or dependency-based), then decide if you're building a table (DP) or just sorting and picking (greedy or two-pointers). Watch out for off-by-one errors in cumulative sums and cases where order matters. StealthCoder will catch the problem structure and steer you toward the right framework when you're under time pressure.
Drill it cold or hedge it with StealthCoder. Either way, don't walk into the OA hoping you remember the trick.
You can drill Minimize Total Input Cost 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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This OA pattern shows up on LeetCode as two city scheduling. If you have time before the OA, drill that.
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Salesforce 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.
Minimize Total Input Cost FAQ
Is this a greedy problem or DP?+
Greedy works if the choice at each step doesn't affect future options. If minimizing one input's cost blocks cheaper combinations later, you need DP with memoization or a full table. Test greedy mentally on small inputs first. If it breaks, switch to DP.
What's the common pitfall candidates hit?+
Assuming the minimum cost input is always the right choice. Often there's a fixed overhead or setup cost that makes a higher-cost input better in aggregate. Read the problem twice for hidden costs and constraints.
How do I prepare for this in 48 hours?+
Drill prefix-sum problems and greedy vs. DP decision trees. Look at problems like "two city scheduling" and "jump game" variants. Understand when sorting changes the game. Write out the cost function explicitly before coding.
Is this still asked at Salesforce?+
Yes. Cost optimization and resource allocation are core to Salesforce's platform. Expect variations on this every cycle. The pattern is durable.
What languages are usually allowed?+
The assessment typically allows Python, Java, C++, and JavaScript. Pick whichever you're fastest in for sorting and DP lookups. Python's min and sorted are your friends here.