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OverviewPrecompute running totals · range sum in O(1)
Count Vowels in SubstringsPrefix-sum a 0/1 indicator
Subarray Sum Equals KRunning prefix + a count hashmap

Heap / Priority Queue21

Binary Search Trees21

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Home/Prefix Sum

Prefix Sum

Precompute running totals — range queries in O(1).

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OverviewPrecompute running totals · range sum in O(1)animatedEasy
Count Vowels in SubstringsPrefix-sum a 0/1 indicatoranimatedMedium
Subarray Sum Equals KRunning prefix + a count hashmapanimatedMedium