Two Pointers & Sliding Windows

Question 1

How does the two-pointer technique work?

Answer 1

Uses two indices to optimize searching.

Question 2

What are common two-pointer use cases?

Answer 2

Sorted Two Sum, Reverse String.

Question 3

What is Sliding Window?

Answer 3

Shrinks and expands a window for optimization.

Question 4

What is the difference between fixed and variable sliding windows?

Answer 4

Fixed has a set size; variable expands/contracts.

Question 5

How do we keep sliding window O(n)?

Answer 5

The left and right pointers should only traverse the array once.

Question 6

What operations happen in a variable size sliding window?

Answer 6

Each element is processed twice: once when expanding, once when contracting.

Question 7

What operations happen in a fixed-size sliding window?

Answer 7

Each element is added to the window once and removed once.