Implement Sorted Singly Linked List in C++

In data structure, Linked List is a linear collection of data elements. Each element or node of a list is comprising of two items - the data and a reference to the next node. The last node has a reference to null. Into a linked list the entry point is called the head of the list.

Each node in the list stores the contents and a pointer or reference to the next node in the list, in a singly linked list. Singly linked list does not store any pointer or reference to the previous node.

Developing a C++ program to implement sorted singly linked list.

Algorithm

Begin
   function createnode() to insert node in the list:
      It checks whether the list is empty or not.
      If the list is empty put the node as first element and update head.
      Initialize the next pointer with NULL.
      If list is not empty,
      It creates a newnode and inserts the number in the data field of the newnode.
      Now the newnode will be inserted in such a way that linked list will remain sorted.
      If it gets inserted at the last, then the newnode points to NULL.
      If the newnode inserted at the first, then the linked list starts from there.
End
Begin
   function display() to print the list content having n number of nodes:
      Initialize c = 0.
      Initialize pointer variable with the start address
      while (c <= n)
         Print the node info
         Update pointer variable
         Increment c.
End

Example Code

#include<iostream>
using namespace std;
struct nod {
   int d;
   nod *n;
}
*p = NULL, *head = NULL, *q = NULL, *np = NULL;
int c = 0;
void createnode(int n) {
   np = new nod;
   np->d = n;
   np->n = NULL;
   if (c == 0) {
      head = np;
      p = head;
      p->n = head;
      c++;
   } else if (c == 1) {
      p = head;
      q = p;
      if (np->d < p->d) {
         np->n = p;
         head = np;
         p->n = np;
      } else if (np->d > p->d) {
         p->n = np;
         np->n = head;
      }
      c++;
   } else {
      p = head;
      q = p;
      if (np->d < p->d) {
         np->n = p;
         head = np;
         do {
            p = p->n;
         }
         while (p->n != q);
            p->n = head;
      } else if (np->d > p->d) {
         while (p->n != head && q->d < np->d) {
            q = p;
            p = p->n;
            if (p->n == head) {
               p->n = np;
               np->n = head;
            } else if (np->d< p->d) {
               q->n = np;
               np->n = p;
               break;
            }
         }
      }
   }
}
void display(int i) {
   nod *t = head;
   int c = 0;
   while (c <= i ) {
      cout<<t->d<<"\t";
      t = t->n;
      c++;
   }
}
int main() {
   int i = 0, n, a;
   cout<<"enter the no of nodes\n";
   cin>>n;
   while (i < n) {
      cout<<"\nenter value of node\n";
      cin>>a;
      createnode(a);
      i++;
   }
   cout<<"sorted singly link list"<<endl;
   display(n);
}

Output

enter the no of nodes
5
enter value of node
6
enter value of node
4
enter value of node
7
enter value of node
3
enter value of node
2
sorted singly link list
2 3 4 6 7 2