{"id":5754,"date":"2021-10-11T08:00:03","date_gmt":"2021-10-11T08:00:03","guid":{"rendered":"https:\/\/www.prepbytes.com\/blog\/?p=5754"},"modified":"2023-07-27T13:02:37","modified_gmt":"2023-07-27T13:02:37","slug":"insert-a-node-at-a-specific-position-in-a-linked-list","status":"publish","type":"post","link":"https:\/\/prepbytes.com\/blog\/insert-a-node-at-a-specific-position-in-a-linked-list\/","title":{"rendered":"Insert a Node at a Specific Position in a Linked List"},"content":{"rendered":"

\"\"<\/p>\n

Linked lists are essential data structures used in computer programming to efficiently store and manage collections of elements. Inserting a new node before a specified position in a singly linked list is a common operation that allows programmers to dynamically expand and modify the list as needed.<\/p>\n

In this article, we will delve into the process of inserting a node before a specified position in a singly linked list using C programming language. We will explore the fundamentals of singly linked lists, understanding the node structure and the connections that form the list. By providing step-by-step explanations and practical examples, readers will gain a comprehensive understanding of how to implement the insert operation effectively. Here we will learn in detail how to insert a node at a specific position in a linked list in C.<\/p>\n

How to Insert a Node at a Specific Position in a Linked List in C?<\/h2>\n

The problem is quite simple. We just have to insert a node at a specific position in a linked list<\/a> in C. Here is an example to understand what is meant by to insert a node at a specific position in a linked list.<\/p>\n

Example :<\/strong><\/p>\n

Input:<\/strong><\/p>\n

list = 1\u21922\u21923\u21924\u21925, \n          data = 6\n          position = 2<\/code><\/pre>\n
Output:<\/strong><\/p>\n
1 \u2192 6 \u2192 2\u2192 3 \u2192 4 \u2192 5<\/code><\/pre>\n
Explanation:<\/strong>
\nSuppose the given list is 1 \u2192 2 \u2192 3 \u2192 4 \u2192 5, position = 2, and the data to be inserted is 6.<\/p>\n
    \n
  • According to the problem statement, we need to insert a node with value = 6 at 2nd position in the linked list.<\/li>\n
  • So, after adding the node with value = 6 at the 2nd position in the given linked list, our resultant list will be 1 \u2192 6 \u2192 2\u2192 3 \u2192 4 \u2192 5.<\/li>\n<\/ul>\n
    Now the problem statement is clear. So, now the main question is how we should approach this problem. What is the first thing that comes to mind when we talk about insertion at a specific position in a linked list?<\/p>\n
      \n
    • List traversal, right? Yes. We are going to use list traversal for insertion at a specific position in a linked list.<\/li>\n<\/ul>\n
      Before moving further to the approach section, try to think of the approach by yourself.<\/p>\n
        \n
      • If stuck, no problem, we will thoroughly see how we can approach this problem in the next section.<\/li>\n<\/ul>\n
        Let\u2019s move to the approach section.<\/p>\n
        Approach to Insert a Node at a Specific Position in a Linked List in C<\/h3>\n
        Our approach to insert at any position in linked list is going to be pretty simple. Here is our approach.<\/p>\n
          \n
        • We will simply traverse till (position -1<\/strong>)th node and add the newnode<\/strong> just after that node.<\/strong> Well, how will this work? Let us take an example.\n
            \n
          • Suppose the list is 1 \u2192 2 \u2192 3, and we have to insert 4 at the 2nd position.<\/li>\n
          • Now, we will traverse (position -1) = (2-1) = 1<\/strong> node and after traversing 1 node, we will be standing at 1.<\/li>\n
          • Now we will make 4 \u2192 next = 1 \u2192 next<\/strong> as we have to insert it after 1, and finally, 1 \u2192 next = 4<\/strong> to link the nodes.<\/li>\n
          • By doing the above steps, 4 will be added at that specific position, and our resultant linked list will be: 1 \u2192 4 \u2192 2 \u2192 3.<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n
            We can get a clearer look at the approach by looking at the dry run.<\/p>\n
            Algorithm to Insert a Node at a Specific Position in a Linked List in C<\/h3>\n
            The algorithm to insert a node at a specific position in a linked list is given below.<\/p>\n
              \n
            • If the position where we are asked to insert pos<\/strong> is smaller than 1 or greater than the size of the list<\/strong>, it is invalid, and we will return.<\/li>\n
            • Else, we will make a variable curr<\/strong> and make it point to the head<\/strong> of the list.<\/li>\n
            • Now we will run a for loop using curr<\/strong> to reach to the node at (pos-1<\/strong>)th position:\n
                \n
              • The for loop will be: for(int i=1;inext;}<\/strong><\/li>\n
              • After the termination of the above loop, curr<\/strong> will be standing at the (position \u2013 1<\/strong>)th node.<\/li>\n
              • As explained above, we will simply make newnode \u2192 next = curr \u2192 next<\/strong> and curr \u2192 next = newnode.<\/strong><\/li>\n<\/ul>\n<\/li>\n
              • If the pos<\/strong> was equal to 1, we will make the head<\/strong> point to newnode<\/strong> as newnode<\/strong> will become the first node of the list.<\/li>\n<\/ul>\n
                Dry Run to Insert a Node at a Specific Position in a Linked List in C<\/h3>\n
                \"\"<\/p>\n
                Now, it is the showdown. Let’s see the code implementation to insert a node from linked list at a given position in C, C++, Java and in Python.<\/p>\n
                Code to Insert a Node at a Specific Position in a Linked List in C<\/h3>\n
                Here is the code implementation for how to insert a node at a specific position in a linked list in C, C++, Java, and Python.
                \nn.<\/p>\n\t\t\t\t\t\t