C++ / Linked List Manipulations Develop a program that will maintain an ordered

Question

C++ / Linked List Manipulations

Develop a program that will maintain an ordered linked list of positive whole numbers. Your program will provide for the following options:

a. Add a number

b. Delete a number

c. Search for a number

d. Display the whole list of numbers

At all times, the program will keep the list ordered (the smallest number first and the largest number last).

At the start of the program, the list will be empty. The user will add new numbers by choosing the "add" option and will supply the number to be included in the list. The program will add the number to the list at the appropriate position in the linked list so that the list will remain ordered.

If the number being added is already in the list, the program will display a message: "Duplicate number. Not added to the list". This will ensure that the list does not contain any duplicate numbers.

For removing a number from the list, the user will choose the "delete" option and supply the number to be removed. If the number is in the list, it will be eliminated from the linked list. Otherwise, a message will be displayed: "Number is not in the list". For looking up a number in the list, the user will choose the "search" option and will provide the number to be found. If the number is in the list, the program will display : "the number is in the list". Otherwise, it will display: “the number is not in the list".

For printing, the complete list of numbers, the user will select the "display" option. This option will display the list of all the numbers in the list. It should be an ordered list of unique numbers.

Instructions: Use the following structure for storing each number. struct entry { int number; entry * next; }

Explanation / Answer

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

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



void append(int num)
{
struct node *temp,*right;
temp= (struct node *)malloc(sizeof(struct node));
temp->data=num;
right=(struct node *)head;
while(right->next != NULL)
right=right->next;
right->next =temp;
right=temp;
right->next=NULL;
}



void add( int num )
{
struct node *temp;
temp=(struct node *)malloc(sizeof(struct node));
temp->data=num;
if (head== NULL)
{
head=temp;
head->next=NULL;
}
else
{
temp->next=head;
head=temp;
}
}
void addafter(int num, int loc)
{
int i;
struct node *temp,*left,*right;
right=head;
for(i=1;i<loc;i++)
{
left=right;
right=right->next;
}
temp=(struct node *)malloc(sizeof(struct node));
temp->data=num;
left->next=temp;
left=temp;
left->next=right;
return;
}



void insert(int num)
{
int c=0;
struct node *temp;
temp=head;
if(temp==NULL)
{
add(num);
}
else
{
while(temp!=NULL)
{
if(temp->data<num)
c++;
temp=temp->next;
}
if(c==0)
add(num);
else if(c<count())
addafter(num,++c);
else
append(num);
}
}



int delete(int num)
{
struct node *temp, *prev;
temp=head;
while(temp!=NULL)
{
if(temp->data==num)
{
if(temp==head)
{
head=temp->next;
free(temp);
return 1;
}
else
{
prev->next=temp->next;
free(temp);
return 1;
}
}
else
{
prev=temp;
temp= temp->next;
}
}
return 0;
}


void display(struct node *r)
{
r=head;
if(r==NULL)
{
return;
}
while(r!=NULL)
{
printf("%d ",r->data);
r=r->next;
}
printf(" ");
}


int count()
{
struct node *n;
int c=0;
n=head;
while(n!=NULL)
{
n=n->next;
c++;
}
return c;
}


int main()
{
int i,num;
struct node *n;
head=NULL;
while(1)
{
printf(" List Operations ");
printf("=============== ");
printf("1.Insert ");
printf("2.Display ");
printf("3.Size ");
printf("4.Delete ");
printf("5.Exit ");
printf("Enter your choice : ");
if(scanf("%d",&i)<=0){
printf("Enter only an Integer ");
exit(0);
} else {
switch(i)
{
case 1: printf("Enter the number to insert : ");
scanf("%d",&num);
insert(num);
break;
case 2: if(head==NULL)
{
printf("List is Empty ");
}
else
{
printf("Element(s) in the list are : ");
}
display(n);
break;
case 3: printf("Size of the list is %d ",count());
break;
case 4: if(head==NULL)
printf("List is Empty ");
else{
printf("Enter the number to delete : ");
scanf("%d",&num);
if(delete(num))
printf("%d deleted successfully ",num);
else
printf("%d not found in the list ",num);
}
break;
case 5: return 0;
default: printf("Invalid option ");
}
}
}
return 0;
}

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