In a class with n students, the final exam grades of the mathematics course are stored on a complete binary tree. $($A complete binary tree is a special type of binary tree in which all levels of the tree are fully populated except the lowest level nodes.$)$ Each node of the grade tree stores a student's math final grade. Assume all students have different grades. If any node in the grade tree has a smaller grade value than all the nodes connected to that node by an edge, that node is called the $$weak node$.$ Describe an algorithm based on a divide$-$and$-$conquer approach that finds one of the weak nodes