Determine if a given array is sorted in non-decreasing order, but may have been rotated. In other words, check if rotating the array could result in a sorted array.

Determine if a linked list exists as a contiguous subpath within a binary tree. The subpath must follow the order of nodes in the linked list.

Find the smallest positive integer that is missing from a given array of integers. You need to do this in linear time and constant extra space.