C++ Program For Insertion Sort In A Singly Linked List
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. 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 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 <bits/stdc++.h>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 codeint 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 Linked List after sorting 3 4 5 20 30
Please refer complete article on Insertion Sort for Singly Linked List for more details!
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