Sliding Window

Given two strings s1 and s2, return true if s2 contains any permutation of s1 as a contiguous substring; otherwise return false. (Equivalently: does a sliding window of size s1.length in s2 have the same character frequencies as s1?)

Given an array of positive integers nums and a positive integer target, return the minimal length of a contiguous subarray whose sum is greater than or equal to target. If no such subarray exists, return 0.

You are visiting a fruit farm where the trees are in a row, represented by an array fruits (each value is a fruit type). You have two baskets and each basket can only hold one type of fruit (no count limit). You start at any tree, must move strictly rightward, and must pick one fruit from every tree until you cannot continue. Return the maximum number of fruits you can pick — equivalently, the longest contiguous subarray containing at most 2 distinct values.

Given a binary array nums, you must delete exactly one element. Return the length of the longest subarray containing only 1s in the resulting array.