# C++ Program For Insertion Sort In A Singly Linked List

• Last Updated : 28 Dec, 2021

We have discussed Insertion Sort for arrays. In this article we are going to discuss Insertion Sort for linked list.
Below is a simple insertion sort algorithm for a linked list.

```1) Create an empty sorted (or result) list.
2) Traverse the given list, do following for every node.
......a) Insert current node in sorted way in sorted or result list.

The main step is (2.a) which has been covered in the post Sorted Insert for Singly Linked List
Below is implementation of above algorithm:

## C++

 `// C++ program to sort link list``// using insertion sort``#include ``using` `namespace` `std;`` ` `struct` `Node ``{``    ``int` `val;``    ``struct` `Node* next;``    ``Node(``int` `x)``    ``{``        ``val = x;``        ``next = NULL;``    ``}``};`` ` `class` `LinkedlistIS ``{``    ``public``:``    ``Node* head;``    ``Node* sorted;`` ` `    ``void` `push(``int` `val)``    ``{``        ``// Allocate node ``        ``Node* newnode = ``new` `Node(val);`` ` `        ``// Link the old list off the ``        ``// new node ``        ``newnode->next = head;``        ``// Move the head to point to the ``        ``// new node ``        ``head = newnode;``    ``}`` ` `    ``// Function to sort a singly linked list ``    ``// using insertion sort``    ``void` `insertionSort(Node* headref)``    ``{``        ``// Initialize sorted linked list``        ``sorted = NULL;``        ``Node* current = headref;`` ` `        ``// Traverse the given linked list ``        ``// and insert every node to sorted``        ``while` `(current != NULL) ``        ``{``            ``// Store next for next iteration``            ``Node* next = current->next;`` ` `            ``// Insert current in sorted ``            ``// linked list``            ``sortedInsert(current);`` ` `            ``// Update current``            ``current = next;``        ``}`` ` `        ``// Update head_ref to point to ``        ``// sorted linked list``        ``head = sorted;``    ``}`` ` `    ``/* Function to insert a new_node in a list. ``       ``Note that this function expects a pointer ``       ``to head_ref as this can modify the head of ``       ``the input linked list (similar to push()) */``    ``void` `sortedInsert(Node* newnode)``    ``{``        ``// Special case for the head end ``        ``if` `(sorted == NULL || ``            ``sorted->val >= newnode->val) ``        ``{``            ``newnode->next = sorted;``            ``sorted = newnode;``        ``}``        ``else` `        ``{``            ``Node* current = sorted;`` ` `            ``/* Locate the node before the ``               ``point of insertion */``            ``while` `(current->next != NULL && ``                   ``current->next->val < newnode->val) ``            ``{``                ``current = current->next;``            ``}``            ``newnode->next = current->next;``            ``current->next = newnode;``        ``}``    ``}`` ` `    ``// Function to print linked list ``    ``void` `printlist(Node* head)``    ``{``        ``while` `(head != NULL) ``        ``{``            ``cout << head->val << ``" "``;``            ``head = head->next;``        ``}``    ``}``};`` ` `// Driver code``int` `main()``{``    ``LinkedlistIS list;``    ``list.head = NULL;``    ``list.push(5);``    ``list.push(20);``    ``list.push(4);``    ``list.push(3);``    ``list.push(30);``    ``cout << ``"Linked List before sorting"` `<< ``             ``endl;``    ``list.printlist(list.head);``    ``cout << endl;``    ``list.insertionSort(list.head);``    ``cout << ``"Linked List After sorting"` `<< ``             ``endl;``    ``list.printlist(list.head);``}``// This code is contributed by nirajgusain5`

Output:

```Linked List before sorting
30  3  4  20  5