Question

Complete the code that inserts elements into a list. The list should always be in an ordered state.

#include <stdio.h>
#include <stdlib.h>

/* list of nodes, each with a single integer */
struct element {
struct element *next;
int value;
};

/* protypes for functions defined after main */
struct element *elementalloc(void);
struct element *listinitialize();
struct element *insertelement(struct element *, int);
void printlist(struct element *);

/* main
* Creates an ordered list
* Elements added to the list must be inserted maintaining the list
* in an ordered state
*/
int main() {
struct element *listhead = NULL;
listhead = listinitialize();
for (int i = 3; i < 100; i+=11){
listhead = insertnewelement(listhead, i);
}
printlist(listhead);
}

/* allocate memory for a new list element */
struct element *elementalloc(void) {
return (struct element *)malloc(sizeof(struct element));
}

/* simple list initialization function */
struct element *listinitialize() {
const int numbers[7] = {4, 9, 13, 18, 27, 49, 60};
struct element *newlist = NULL;
struct element *tail = NULL;
struct element *temp = NULL;
for (int i = 0; i < 7; i++) {
if (newlist == NULL) {
newlist = elementalloc();
newlist->next = NULL;
newlist->value = numbers[i];
tail = newlist;
} else {
temp = elementalloc();
temp->value = numbers[i];
temp->next = NULL;
tail->next = temp;
tail = tail->next;
}
}
return newlist;
}

/* function to insert elements into an ordered list */
struct element *insertnewelement(struct element *listhead, int x) {
struct element *newelement;
newelement = elementalloc();

struct element *iter = listhead;
while( ) {

}

return listhead;
}

/* print the list and the respective memory locations in list order */
void printlist(struct element *listhead)
{
while (listhead != NULL) {
printf("Memory: %p contains value: %d\n", listhead, listhead->value);
listhead = listhead->next;
}
}

Answer 1

Please look at my code and in case of indentation issues check the screenshots.

------------main.c----------------

#include <stdio.h>
#include <stdlib.h>

/*list of nodes, each with a single integer */
struct element
{
   struct element * next;
   int value;
};

/*protypes for functions defined after main */
struct element* elementalloc(void);
struct element* listinitialize();
struct element* insertnewelement(struct element *, int);
void printlist(struct element *);

/*main
*Creates an ordered list
*Elements added to the list must be inserted maintaining the list
*in an ordered state
*/
int main()
{
   struct element *listhead = NULL;
   listhead = listinitialize();
   printlist(listhead);
   for (int i = 3; i < 100; i += 11)
   {
       listhead = insertnewelement(listhead, i);
   }
   printf("\n\n");
   printlist(listhead);
}

/*allocate memory for a new list element */
struct element* elementalloc(void)
{
   return (struct element *) malloc(sizeof(struct element));
}

/*simple list initialization function */
struct element* listinitialize()
{
   const int numbers[7] = { 4, 9, 13, 18, 27, 49, 60 };
   struct element *newlist = NULL;
   struct element *tail = NULL;
   struct element *temp = NULL;
   for (int i = 0; i < 7; i++)
   {
       if (newlist == NULL)
       {
           newlist = elementalloc();
           newlist->next = NULL;
           newlist->value = numbers[i];
           tail = newlist;
       }
       else
       {
           temp = elementalloc();
           temp->value = numbers[i];
           temp->next = NULL;
           tail->next = temp;
           tail = tail->next;
       }
   }
   return newlist;
}

/*function to insert elements into an ordered list */
struct element* insertnewelement(struct element *listhead, int x)
{
   struct element * newelement;
   newelement = elementalloc();       //allocate the memory for the new element
   newelement->value = x;               //assign the value x to the new element

   if (listhead == NULL){               //check if the list is empty
       listhead = newelement;            //if list is empty the head will point to the new element, next will be NULL
       listhead->next = NULL;
       return listhead;
   }

   if (listhead->value > x){           //check if the new element's value is less than head, then insert newelement at the beginning
       newelement->next = listhead;   
       listhead = newelement;            //new element will become the listhead
       return listhead;
   }  

   struct element *iter = listhead;   //create an iterator pointer

   while (iter->next != NULL && iter->next->value < x) //loop through the elements which are smaller, than x
   {
       iter = iter->next;               //move to next element
   }                                   //when the loop ends iter->next will have value larger than x
   newelement->next = iter->next;       //update the newelement's next element as iter->next
   iter->next = newelement;            //iter will point to newelement

   return listhead;
}

/*print the list and the respective memory locations in list order */
void printlist(struct element *listhead)
{
   while (listhead != NULL)
   {
       printf("Memory: %p contains value: %d\n", listhead, listhead->value);
       listhead = listhead->next;
   }
}

--------------Screenshots-------------------

------------Output-----------------

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