// http://www.cprogramming.com/snippets/source-code/singly-linked-list-insert-remove-add-count
// 4/24/2015 - lrb - minor edits

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

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("\n");
}

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