$(10p)$

struct node $\{$

int data; struct node $*$ leftChild; struct node $*$ rightChild; $)$;

a$)(5$ p$)$ Write pseudo$-$code of the algorithm $($or C code$)$ to calculate the total number of external nodes in a binary search tree.

int totalExternalNodes$($struct node $*$ tree$)$

b$)(5$ p$)$ Write a function $($C$++$ code$)$ to print all the data values of nodes in a binary search tree using pre$-$order walk.

void printPreOrder$($struct node $*$ tree$)$