Programming Fundamentals

Download list_delete_second_last.c here

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1511 fetch-activity list_delete_second_last

Your task is to add code to this function in list_delete_second_last.c: 

//
// Delete the second last node in the list.
// The deleted node is freed.
// The head of the list is returned.
//
struct node *delete_second_last(struct node *head) {

    // PUT YOUR CODE HERE (change the next line!)
    return NULL;
}

Note list_delete_second_last.c uses the following familiar data type:

struct node {
    struct node *next;
    int          data;
};

delete_second_last is given one argument, head, which is the pointer to the first node in a linked list.

Add code to delete_second_last so that it deletes the second last node from list.

delete_second_last should return a pointer to the new list.

If the list is empty, delete_second_last should return NULL.

If the list has exactly one element, delete_second_last should return that one element unchanged.

delete_second_last should call free to free the memory of the node it deletes.

For example if the linked list contains these 8 elements:

16, 7, 8, 12, 13, 19, 21, 12

delete_second_last should return a pointer to a list with these elements:

16, 7, 8, 12, 13, 19, 12

Testing

list_delete_second_last.c also contains a main function which allows you to test your delete_second_last function.

This main function:

Do not change this main function. If you want to change it, you have misread the question.

Your delete_second_last function will be called directly in marking. The main function is only to let you test your delete_second_last function

Examples

dcc list_delete_second_last.c -o list_delete_second_last
./list_delete_second_last 16 7 8 12 13 19 21 12
[16, 7, 8, 12, 13, 19, 12]
./list_delete_second_last 2 4 6 2 4 6
[2, 4, 6, 2, 6]
./list_delete_second_last 42
[42]
./list_delete_second_last
[]

Assumptions/Restrictions/Clarifications