单链表的插入排序
原文：https://www.geeksforgeeks.org/insertion-sort-for-singly-linked-list/
我们已经讨论了数组的插入排序。 在本文中，讨论了相同的链表。
以下是链表的简单插入排序算法。
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.
主要步骤是（2.a），已在下面的文章中介绍。
下面是上述算法的实现
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;
}
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
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 = None
a = 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
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
输出：
Linked List before sorting
30 3 4 20 5
Linked List after sorting
3 4 5 20 30
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