Two Pointers on Arrays and Strings

Context

The two pointers technique is a common interview pattern for reducing nested-loop scans into linear-time solutions on arrays and strings. Interviewers expect you to recognize when sequential structure allows two indices to move intelligently.

Core Question

Explain how you would solve a two pointers problem on an array or string.

Your answer should address:

1. What the two pointers technique is and why it can improve performance.
2. The main pointer movement patterns, such as moving from both ends or using a sliding window.
3. How to decide pointer updates based on the problem goal and input properties.

Scope Guidance

Go beyond a definition. The interviewer expects you to describe the intuition, common use cases, complexity trade-offs, and a few representative examples such as palindrome checking, pair sum in a sorted array, or removing duplicates in place.