Solve linked list reversal and minima problems

You are given three independent coding tasks. ## 1) Reverse a singly linked list **Input:** The head of a singly linked list. **Output:** The head of the same list with nodes reversed. **Constraints / Notes:** - Aim for \(O(n)\) time. - Prefer \(O(1)\) extra space (iterative), but you may also discuss a recursive approach. --- ## 2) Find the minimum number in a rotated matrix Assume the matrix represents a *rotated sorted sequence* when read in row-major order: - If you flatten the \(m \times n\) matrix into an array in row-major order, that flattened array was originally sorted in strictly increasing order and then rotated (circularly shifted) by an unknown offset. **Input:** An \(m \times n\) integer matrix `mat` with `m,n >= 1` satisfying the property above. **Output:** The minimum value in the matrix. **Constraints / Notes:** - Target \(O(\log(mn))\) time by using binary search over the implicit flattened array. --- ## 3) Find the minimum value in a linked list **Input:** The head of a singly linked list of integers (not necessarily sorted). **Output:** The minimum integer value contained in the list. **Constraints / Notes:** - \(O(n)\) time, \(O(1)\) extra space. - Specify what to do if the list is empty (e.g., return `null`/raise an exception).