What is the sliding window pattern and what types of problems does it solve?

The sliding window pattern maintains a window of elements that slides through an array or string, processing elements as they enter and leave the window. It solves problems involving contiguous subarrays or substrings, such as finding the maximum sum subarray of size k, the longest substring without repeating characters, or the smallest subarray with a sum greater than a target. The window is defined by left and right pointers. Fixed-size windows move both pointers together. Dynamic-size windows expand the right pointer and contract the left pointer based on a condition.