Tagged “interview”

1 post found.

Tutorials

How to study this material without drowning Data Structure & Algorithm · 2 min read Handling a DP question under pressure Data Structure & Algorithm · 3 min read Pattern recognition — reading the problem for its solution Data Structure & Algorithm · 2 min read Testing your solution before they do Data Structure & Algorithm · 2 min read A practice plan that holds Data Structure & Algorithm · 2 min read Three problems, worked end to end Data Structure & Algorithm · 3 min read

Jul 6, 2026· 2 min read ·114 views

The sliding window, four patterns deep

Turning O(n·k) into O(n) by not throwing away work you already did

Key takeaways

When windows overlap, do not rebuild them — update them.
The inner while loop is still O(n): left only ever moves forward.
Contiguous means window; subsequence does not.

Most array problems have an obvious brute force answer: check every window, take the best one. It works, and it is O(n·k). Consecutive windows overlap almost completely. Only one e…