The discount logic is where I got sloppy at first.
Start by clarifying the problem requirements and constraints, then design a data model that tracks purchased cards and their discount effects. Implement canPurchase to check affordability after applying discounts, and purchase to update the player's inventory and discount state.
Pro tip: Discuss how you would handle edge cases like insufficient gems, duplicate purchases, and discount stacking, and mention potential optimizations for large card sets.
Ask questions to understand the discount rules, whether discounts stack, and if cards can be purchased multiple times. Confirm the expected inputs and outputs for both methods.
Choose data structures to represent the player's gem inventory, purchased cards, and the discount each card provides. Consider using a map to track discounts per card type.
Calculate the effective cost of the target card by applying all applicable discounts from previously purchased cards. Compare this cost with the player's current gems and return a boolean.
If canPurchase returns true, deduct the effective cost from the player's gems, add the card to the purchased list, and update any discount effects for future purchases.
Walk through examples to verify correctness, including edge cases. Discuss time and space complexity and suggest optimizations if needed.
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