Answer:
node*
Step-by-step explanation:
The argument 'head_ptr' is the head-pointer for the following linked list so the data type of the following argument 'head_ptr' is 'node*' in the method 'f()' because the following method 'f()' computed the linked list, but perhaps the list itself remains unaffected.
A linked list is the DS type in which that component would be a different entity. Such component of the following list is called as a node that consists of two elements