Fast & Slow Pointers · Fast-slow and cycle
Detect Cycle in a Linked List
LeetCode 141 · Module: Pointers & Windows
The scenario
you are tracking a live segment — the active users, the current substring, the open interval — and the answer changes as the boundaries move.
What you'll learn
- How to recognize the Fast & Slow Pointers pattern from the problem statement.
- The BASIC Framework breakdown for this problem.
- A clean, interview-ready Python solution with time/space analysis.
Full video, code, and the workspace are part of PatternMastery Pro — 500 problems for one $9.99 payment.