Pattern 1 · 10 problems
Array & Traversal
Concepts: Linear scan, prefix/suffix, simulation.
Signal: One pass over an array, running min/max, or left×right products.
Concept walkthrough
best = init; state = init for x in nums: update state with x best = improve(best, state) return best
What this pattern is
Most interview problems start as an array scan. Master a clean left-to-right pass, then layer prefix/suffix products, running minima, and in-place swaps. Before any fancy pattern, ask: “Can one linear pass with O(1) or O(n) extra memory solve this?”
When do I use this?
- ✓ Need a single answer from scanning once or twice
- ✓ Prefix / suffix products or running sums
- ✓ In-place rearrange (move zeroes, rotate)
- ✓ Kadane-style contiguous optimum
Interview template
Memorize the shape, not a specific problem.
best = init; state = init for x in nums: update state with x best = improve(best, state) return best