Give the prefix, infix and postfix expressions corresponding to the following tree: a b d A node in the binary tree in problems 2, 3 and 4 below is represented with the following data structure: struct Node { int key; Node *left, *right; // pointers to the left and right children }; Problem 2 (20 points) Complete the code of a recursive function removeAllLeaves below that takes a pointer to the root node of a tree T and returns a pointer to the root node of the tree that results from removing all leaves from T // remove the leaf nodes from a given tree and return a pointer to the root of the modified tree Node remove AllLeaves (Node* root) {