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Prefix Sum Technique

DifficultyEasy to Medium
Used InArrays, Range Queries, Cumulative Sums

Master the preprocessing technique that transforms O(n) range calculations into O(1) lookups, enabling lightning-fast queries on subarray sums and aggregations.

🏗️Building a Foundation

Imagine you're constructing a skyscraper. Would you check the strength of each beam and column every single time someone asks if the building is structurally sound? Of course not!

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The Foundation Principle

Instead, you'd calculate the structural integrity once, document it thoroughly, and simply reference those calculations whenever questions arise. This is exactly how prefix sums operate—building a solid foundation of preprocessed data that makes future queries lightning-fast.

Just as engineers invest time in laying proper groundwork before a building rises, prefix sums teach us the importance of strategic preparation. In life, we often face recurring questions or challenges. By investing time upfront to build strong foundations—whether in education, relationships, or skills—we can navigate future challenges with remarkable efficiency.

The lesson

"The time invested in building strong foundations today will exponentially reduce the effort needed to solve tomorrow's problems."

Legend

Processed Element
Selected Range