Prefix Sum
ProUse when you need to efficiently compute range sums, find subarrays with a target sum, or answer multiple cumulative queries on an array.
Use when you need to efficiently compute range sums, find subarrays with a target sum or property, or answer multiple cumulative queries on an array.
Keywords for identifying Prefix Sum Problems
→ Range sum / subarray sum query
→ Find subarray with target sum / divisible by k
→ Contiguous subarray with property (equal count, sum equals k)
→ Product of array except self
→ Multiple range queries on same array
→ Cumulative sum / running total
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