Tech article
Understanding Prefix Sum with a Practical Example (Pocket Money Tracker)
Community description: Prefix Sum is a simple but powerful technique used in many array problems instead of recalculating...
Dev.to | Mar 10, 2026 | Nithya Dharshini official
Automated excerpt
How much did you spend from Day 2 to Day 4? Prefix sum stores the running total of expenses. Now suppose we want the total from Day 2 to Day 4. int result = (L == 0) ? pref[R] : pref[R] - pref[L-1]; This is extremely useful when we have many range queries.
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