Understand how arrays work, how memory and indexing behave, and how to reason about basic array operations.
Before you start
Estimated learning time · 30–45 minPractice target · 8 problems
Why these problems
Eight problems that move from plain traversal to prefix/suffix reasoning. Each one adds exactly one new idea, so the set is short on purpose.
Solved0 / 8
Practice these 8
0 / 8 solved
1929Concatenation of ArrayEasy
Why this problem — Basic traversal and indexing
1480Running Sum of 1d ArrayEasy
Why this problem — Iteration and maintaining state
1470Shuffle the ArrayEasy
Why this problem — Index manipulation
1431Kids With the Greatest Number of CandiesEasy
Why this problem — Traversal and comparisons
217Contains DuplicateEasy
Why this problem — Array scanning and introducing set-based thinking
1Two SumEasy
Why this problem — Core array problem and complexity tradeoffs
121Best Time to Buy and Sell StockEasy
Why this problem — Single-pass reasoning and maintaining state
238Product of Array Except SelfMedium
Why this problem — Prefix/suffix reasoning and space optimization