Prefix Sum Problems

Practise 25 prefix sum problems from basics to advanced in Python, C++, Java, JavaScript and TypeScript.

This track covers running totals, range queries, difference arrays, subarray sums with hash maps, 2-D prefix sums and XOR prefixes. The problems run from easy to hard, so each idea builds on the one before. Every problem is judged against hidden test cases in five languages.

What you will practise:

• Basics: 9 easy problems such as Cumulative Steps, Exactly K Coverage and Rain Gauge Log.
• Core Problems: 11 medium problems such as Divisible Stretches, Tiring Stretch and Product of the Tail.
• Hard Problems: 5 hard problems such as Target Rectangles, Capped Rectangle Sum and Weighted Equaliser.

Start with the basics, move on to the core problems, and try the hard ones when the pattern feels natural. Every problem comes with worked examples and clear constraints. For a full path across all of DSA, see Revquix 80, Revquix 150 and Revquix 300.