Javascript Program For Recursive Selection Sort For Singly Linked List – Swapping Node Links

Last Updated : 03 Sep, 2024

Given a singly linked list containing n nodes. The problem is to sort the list using the recursive selection sort technique. The approach should be such that it involves swapping node links instead of swapping node data.

sorting image

Examples:

Input: 10 -> 12 -> 8 -> 4 -> 6
Output: 4 -> 6 -> 8 -> 10 -> 12

In Selection Sort, we first find the minimum element, swap it with the beginning node and recur for the remaining list. Below is the recursive implementation of these steps for the linked list.

recurSelectionSort(head)
     if head->next == NULL
         return head
     Initialize min = head
     Initialize beforeMin = NULL
     Initialize ptr = head
    
     while ptr->next != NULL 
         if min->data > ptr->next->data
         min = ptr->next
         beforeMin = ptr
     ptr = ptr->next    
    
     if min != head
         swapNodes(&head, head, min, beforeMin)
    
     head->next = recurSelectionSort(head->next)
     return head

swapNodes(head_ref, currX, currY, prevY)
     head_ref = currY
     prevY->next = currX

     Initialize temp = currY->next
     currY->next = currX->next
     currX->next  = temp

The swapNodes(head_ref, currX, currY, prevY) is based on the approach discussed here but it has been modified accordingly for the implementation of this post.

JavaScript

// Javascript implementation of recursive  // selection sort for singly linked list  // | Swapping node links       // A Linked list node class Node  {     constructor(val)      {         this.data = val;         this.next = null;     } }  // Function to swap nodes 'currX' and  // 'currY' in a linked list without  // swapping data function swapNodes(head_ref, currX,                      currY,  prevY)  {     // Make 'currY' as new head     head_ref = currY;      // Adjust links     prevY.next = currX;      // Swap next pointers     let temp = currY.next;     currY.next = currX.next;     currX.next = temp;     return head_ref; }  // Function to sort the linked list using // recursive selection sort technique function recurSelectionSort(head)  {     // If there is only a single node     if (head.next == null)         return head;       // 'min' - pointer to store the node       // having minimum data value      let min = head;       // 'beforeMin' - pointer to store node       // previous to 'min' node      let beforeMin = null;      let ptr;       // Traverse the list till the last node      for (ptr = head; ptr.next != null;            ptr = ptr.next)       {          // if true, then update 'min' and           // 'beforeMin'          if (ptr.next.data < min.data)           {              min = ptr.next;              beforeMin = ptr;          }      }       // if 'min' and 'head' are not same,      // swap the head node with the 'min' node      if (min != head)          head = swapNodes(head, head,                            min, beforeMin);       // recursively sort the remaining list      head.next = recurSelectionSort(head.next);       return head; }  // Function to sort the given linked list function sort(head_ref)  {     // If list is empty     if ((head_ref) == null)         return null;      // Sort the list using recursive      // selection sort technique     head_ref = recurSelectionSort(head_ref);     return head_ref; }  // Function to insert a node at the // beginning of the linked list function push(head_ref, new_data)  {     // Allocate node     let new_node = new Node();      // Put in the data     new_node.data = new_data;      // Link the old list to the      // new node     new_node.next = (head_ref);      // Move the head to point to the      // new node     (head_ref) = new_node;     return head_ref; }  // Function to print the linked list function printList(head)  {     while (head != null)      {         console.log(head.data + " ");         head = head.next;     } }  // Driver code let head = null;  // Create linked list 10.12.8.4.6 head = push(head, 6); head = push(head, 4); head = push(head, 8); head = push(head, 12); head = push(head, 10);  console.log("Linked list before sorting:"); printList(head);  // Sort the linked list head = sort(head);  console.log("Linked list after sorting:"); printList(head); // This code is contributed by todaysgaurav

Output

Linked list before sorting: 10  12  8  4  6  Linked list after sorting: 4  6  8  10  12

Complexity Analysis:

Time Complexity: O(n²)
Auxiliary Space: O(n)

Please refer complete article on Recursive selection sort for singly linked list | Swapping node links for more details!

Javascript Program For Sorting An Array Of 0s, 1s and 2s

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Javascript Program For Recursive Selection Sort For Singly Linked List – Swapping Node Links

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