Latest articles, tutorials, and deep dives from ndlab tech blog.
Stacks feel easy until the interviewer asks for a queue using two stacks. Learn the monotonic stack, deque patterns, and the BFS connection that unlocks hard O(n) solutions.
Linked lists look simple until live pressure hits. Master reversal, cycle detection, the runner technique, and merging — with the mental model that kills null pointer errors.
The hash map improves interview performance more than any other structure. Learn how it works, when O(1) breaks, and the 5 patterns covering 80% of hash-related problems.
Arrays and strings appear in 40%+ of interviews and hide surprising complexity. Master prefix sums, sliding windows, two pointers, and in-place tricks that turn O(n²) into O(n).
Every interview problem hides one of 14 patterns. Stop grinding LeetCode blind — recognize the right pattern in 30 seconds with trigger signals, templates, and a decision tree.
Big-O is the language interviewers speak. Get it wrong and you sound amateur — no matter how clever your solution. Build real intuition from O(1) to O(n!), plus a cheat sheet.
Results