Insertion Sort for Singly Linked List
We have discussed Insertion Sort for arrays. In this article same for linked list is discussed.
Below is simple insertion sort algorithm for 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. 3) Change head of given linked list to head of sorted (or result) list.
The main step is (2.a) which has been covered in below post.
Sorted Insert for Singly Linked List
Below is implementation of above algorithm
C/C++
/* C program for insertion sort on a linked list */#include<stdio.h> #include<stdlib.h> /* Link list node */struct Node { int data; struct Node* next; }; // Function to insert a given node in a sorted linked list void sortedInsert(struct Node**, struct Node*); // function to sort a singly linked list using insertion sort void insertionSort(struct Node **head_ref) { // Initialize sorted linked list struct Node *sorted = NULL; // Traverse the given linked list and insert every // node to sorted struct Node *current = *head_ref; while (current != NULL) { // Store next for next iteration struct Node *next = current->next; // insert current in sorted linked list sortedInsert(&sorted, current); // Update current current = next; } // Update head_ref to point to sorted linked list *head_ref = 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(struct Node** head_ref, struct Node* new_node) { struct Node* current; /* Special case for the head end */ if (*head_ref == NULL || (*head_ref)->data >= new_node->data) { new_node->next = *head_ref; *head_ref = new_node; } else { /* Locate the node before the point of insertion */ current = *head_ref; while (current->next!=NULL && current->next->data < new_node->data) { current = current->next; } new_node->next = current->next; current->next = new_node; } } /* BELOW FUNCTIONS ARE JUST UTILITY TO TEST sortedInsert */ /* Function to print linked list */void printList(struct Node *head) { struct Node *temp = head; while(temp != NULL) { printf("%d ", temp->data); temp = temp->next; } } /* A utility function to insert a node at the beginning of linked list */void push(struct Node** head_ref, int new_data) { /* allocate node */ struct Node* new_node = new Node; /* put in the data */ new_node->data = new_data; /* link the old list off the new node */ new_node->next = (*head_ref); /* move the head to point to the new node */ (*head_ref) = new_node; } // Driver program to test above functions int main() { struct Node *a = NULL; push(&a, 5); push(&a, 20); push(&a, 4); push(&a, 3); push(&a, 30); printf("Linked List before sorting \n"); printList(a); insertionSort(&a); printf("\nLinked List after sorting \n"); printList(a); return 0; } |
chevron_right
filter_none
Java
// Java program to sort link list // using insertion sort public class LinkedlistIS { node head; node sorted; class node { int val; node next; public node(int val) { this.val = val; } } 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) { System.out.print(head.val + " "); head = head.next; } } // Driver program to test above functions public static void main(String[] args) { LinkedlistIS list = new LinkedlistIS(); list.push(5); list.push(20); list.push(4); list.push(3); list.push(30); System.out.println("Linked List before Sorting.."); list.printlist(list.head); list.insertionSort(list.head); System.out.println("\nLinkedList After sorting"); list.printlist(list.head); } } // This code is contributed by Rishabh Mahrsee |
chevron_right
filter_none
Python
# Pyhton implementation of above algorithm # Node class class Node: # Constructor to initialize the node object def __init__(self, data): self.data = data self.next = None # function to sort a singly linked list using insertion sort def insertionSort(head_ref): # Initialize sorted linked list sorted = None # Traverse the given linked list and insert every # node to sorted current = head_ref while (current != None): # Store next for next iteration next = current.next # insert current in sorted linked list sorted = sortedInsert(sorted, current) # Update current current = next # Update head_ref to point to sorted linked list head_ref = sorted return head_ref # 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()) def sortedInsert(head_ref, new_node): current = None # Special case for the head end */ if (head_ref == None or (head_ref).data >= new_node.data): new_node.next = head_ref head_ref = new_node else: # Locate the node before the point of insertion current = head_ref while (current.next != None and current.next.data < new_node.data): current = current.next new_node.next = current.next current.next = new_node return head_ref # BELOW FUNCTIONS ARE JUST UTILITY TO TEST sortedInsert # Function to print linked list */ def printList(head): temp = head while(temp != None): print( temp.data, end = " ") temp = temp.next # A utility function to insert a node # at the beginning of linked list def push( head_ref, new_data): # allocate node new_node = Node(0) # put in the data new_node.data = new_data # link the old list off the new node new_node.next = (head_ref) # move the head to point to the new node (head_ref) = new_node return head_ref # Driver program to test above functions a = Nonea = push(a, 5) a = push(a, 20) a = push(a, 4) a = push(a, 3) a = push(a, 30) print("Linked List before sorting ") printList(a) a = insertionSort(a) print("\nLinked List after sorting ") printList(a) # This code is contributed by Arnab Kundu |
chevron_right
filter_none
C#
// C# program to sort link list // using insertion sort using System; public class LinkedlistIS { public node head; public node sorted; public class node { public int val; public node next; public node(int val) { this.val = val; } } 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) { Console.Write(head.val + " "); head = head.next; } } // Driver code public static void Main(String[] args) { LinkedlistIS list = new LinkedlistIS(); list.push(5); list.push(20); list.push(4); list.push(3); list.push(30); Console.WriteLine("Linked List before Sorting.."); list.printlist(list.head); list.insertionSort(list.head); Console.WriteLine("\nLinkedList After sorting"); list.printlist(list.head); } } // This code contributed by Rajput-Ji |
chevron_right
filter_none
Output:
Linked List before sorting 30 3 4 20 5 Linked List after sorting 3 4 5 20 30
Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above
Attention reader! Don’t stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.
