Question

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

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#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 find the requested program below. Also including the screenshot of sample output and screenshot of code to understand the indentation.

Please provide your feedback
Thanks and Happy learning!

#include <stdio.h>
#include <stdlib.h>
#include <malloc.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 *);



/* 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();

    //Initialize the new element node with values
    newelement->value = x;
    newelement->next = NULL;

    struct element *iter = listhead;
    struct element *prev = NULL;
    bool bInserted = false;

    //Check if the new element is going to be the first elemnt in the list
    //That means the given listhead was NULL
    if (listhead == NULL)
    {
        listhead = newelement;
    }
    else
    {
        //This means there is atleast one elemnt in the given list
        while (iter != NULL) {
            if (x <= iter->value)
            {
                //Check whether the element should be added in the front of the list
                if (prev == NULL)
                {
                    newelement->next = iter;
                    listhead = newelement;
                    bInserted = true;
                    break;
                }
                else //ie prev != NULL
                {
                    newelement->next = prev->next;
                    prev->next = newelement;
                    bInserted = true;
                    break;
                    //}
                }
            }
            prev = iter;
            iter = iter->next;
        }

        if (bInserted != true)
        {
            //This means the elemnt needs to be added as the last node in the list
            prev->next = 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;
    }
}

/* 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);
    return 0;
}