Implement stacks, median, and tree path sum

Implement or discuss the following coding tasks. 1. Design a MinStack data structure that supports push, pop, top, and getMin in O(1) time. 2. Design a MaxStack that supports push, pop, top, peekMax, and popMax. Aim for constant-time top and efficient maximum operations. 3. Given a stream of numbers, design a data structure that can return the current median after each insertion. If helpful, explain whether ideas from the MaxStack design can or cannot be adapted. 4. Given a binary tree with integer values and a target sum, determine whether there exists a path whose endpoints are a node and one of its ancestors, so the path moves only upward from child to parent, and the sum of the values on that path equals the target. A single node counts as a valid path. You may preprocess parent pointers if needed.