Calculate trapped water between elevation bars
TeslaSoftware Engineer · Technical Screen
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This question evaluates array manipulation, algorithmic optimization, and complexity analysis, specifically the ability to reason about time and space trade-offs and design a linear-time, constant-space approach for computing trapped water.
Given an array of non-negative integers representing the heights of unit-width vertical bars, compute the total water retained after rainfall. Start by presenting a brute-force approach and analyze its time and space complexity. Then optimize to a linear-time solution that uses constant extra space, explain the intuition, and implement the final method.
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