使用 Deque 隔离链表中的偶数和奇数节点

给定一个整数链表。任务是编写一个程序来修改链表，使得所有偶数出现在修改后的链表中所有奇数之前。不需要保持偶数和奇数节点的顺序与原始列表的顺序相同，任务只是重新排列节点，使所有偶数节点都出现在奇数节点之前。
另请参阅：隔离链表中的偶数和奇数节点
例子：

Input: 1 -> 2 -> 3 -> 4 -> 5 -> 6 -> 7 -> 8 -> 9 -> 10 -> NULL 
Output: 10 -> 8 -> 6 -> 4 -> 2 -> 1 -> 3 -> 5 -> 7 -> 9 -> NULL
Input: 4 -> 3 -> 2 -> 1 -> NULL 
Output: 2 -> 4 -> 3 -> 1 -> NULL 

这个想法是根据以下条件迭代地将链表的所有元素推送到双端队列：

• 开始遍历链表，如果元素是偶数，则将其推送到 Deque 的前面，然后，
• 如果元素是奇数，则将其推到 Deque 的后面。

最后，从第一个元素开始，用 Deque 的元素替换链表的所有元素。
下面是上述方法的实现：

C++

// CPP program to segregate even and
// odd noeds in a linked list using deque
#include 
using namespace std;
 
/* Link list node */
struct Node {
    int data;
    struct Node* next;
};
 
/*UTILITY FUNCTIONS*/
/* Push a node to linked list. Note that this function
changes the head */
void push(struct Node** head_ref, char new_data)
{
    /* allocate node */
    struct Node* new_node = (struct Node*)malloc(sizeof(struct 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 pochar to the new node */
    (*head_ref) = new_node;
}
 
// printing the linked list
void printList(struct Node* head)
{
    struct Node* temp = head;
    while (temp != NULL) {
                printf("%d ", temp->data);
        temp = temp->next;
    }
}
 
// Function to rearrange even and odd
// elements in a linked list using deque
void evenOdd(struct Node* head)
{
    struct Node* temp = head;
     
    // Declaring a Deque
    deque d;
 
    // Push all the elements of
    // linked list in to deque
    while (temp != NULL) {
 
        // if element is even push it
        // to front of the deque
        if (temp->data % 2 == 0)
            d.push_front(temp->data);
 
        else // else push at the back of the deque
            d.push_back(temp->data);
        temp = temp->next; // increase temp
    }
     
    temp = head;
     
    // Replace all elements of the linked list
    // with the elements of Deque starting from
    // the first element
    while (!d.empty()) {
        temp->data = d.front();
        d.pop_front();
        temp = temp->next;
    }
}
 
// Driver code
int main()
{
    struct Node* head = NULL;
    push(&head, 10);
    push(&head, 9);
    push(&head, 8);
    push(&head, 7);
    push(&head, 6);
    push(&head, 5);
    push(&head, 4);
    push(&head, 3);
    push(&head, 2);
    push(&head, 1);
     
    cout << "Given linked list: ";
        printList(head);
         
    evenOdd(head);
     
    cout << "\nAfter rearrangement: ";
        printList(head);
         
    return 0;
}

Java

// JAVA program to segregate
// even and odd noeds in a
// linked list using deque
import java.util.*;
class GFG{
 
// Link list node
static class Node
{ 
  int data;
  Node next;
};
 
// UTILITY FUNCTIONS
// Push a node to linked list.
// Note that this function
// changes the head
static Node push(Node head_ref,
                 int new_data)
{
  // allocate node
  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 pochar
  // to the new node
  head_ref = new_node;
  return head_ref;
}
 
// Printing the linked list
static void printList(Node head)
{
  Node temp = head;
  while (temp != null)
  {
    System.out.printf("%d ",
                      temp.data);
    temp = temp.next;
  }
}
 
// Function to rearrange even
// and odd elements in a linked
// list using deque
static void evenOdd(Node head)
{
  Node temp = head;
 
  // Declaring a Deque
  Deque d =
        new LinkedList<>();
 
  // Push all the elements of
  // linked list in to deque
  while (temp != null)
  {
    // if element is even push it
    // to front of the deque
    if (temp.data % 2 == 0)
      d.addFirst(temp.data);
 
    else
       
      // else push at the
      // back of the deque
      d.add(temp.data);
     
    // increase temp
    temp = temp.next;
  }
 
  temp = head;
 
  // Replace all elements of
  // the linked list with the
  // elements of Deque starting
  // from the first element
  while (!d.isEmpty())
  {
    temp.data = d.peek();
    d.pollFirst();
    temp = temp.next;
  }
}
 
// Driver code
public static void main(String[] args)
{
  Node head = null;
  head = push(head, 10);
  head = push(head, 9);
  head = push(head, 8);
  head = push(head, 7);
  head = push(head, 6);
  head = push(head, 5);
  head = push(head, 4);
  head = push(head, 3);
  head = push(head, 2);
  head = push(head, 1);
 
  System.out.print("Given linked list: ");
  printList(head);
 
  evenOdd(head);
 
  System.out.print("\nAfter rearrangement: ");
  printList(head);        
}
}
 
// This code is contributed by shikhasingrajput

Python

# Python program to segregate even and
# odd noeds in a linked list using deque
import collections
 
# Node class
class Node:
     
    # Function to initialise the node object
    def __init__(self, data):
        self.data = data # Assign data
        self.next = None
 
# UTILITY FUNCTIONS
# Push a node to linked list. Note that this function
# changes the head
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 pochar to the new node
    (head_ref) = new_node
     
    return head_ref
 
# printing the linked list
def printList( head):
 
    temp = head
    while (temp != None):
        print( temp.data, end = " ")
        temp = temp.next
     
# Function to rearrange even and odd
# elements in a linked list using deque
def evenOdd( head):
 
    temp = head
     
    # Declaring a Deque
    d = collections.deque([])
 
    # Push all the elements of
    # linked list in to deque
    while (temp != None) :
 
        # if element is even push it
        # to front of the deque
        if (temp.data % 2 == 0):
            d.appendleft(temp.data)
 
        else: # else push at the back of the deque
            d.append(temp.data)
        temp = temp.next # increase temp
     
    temp = head
     
    # Replace all elements of the linked list
    # with the elements of Deque starting from
    # the first element
    while (len(d) > 0) :
        temp.data = d[0]
        d.popleft()
        temp = temp.next
     
# Driver code
 
head = None
head = push(head, 10)
head = push(head, 9)
head = push(head, 8)
head = push(head, 7)
head = push(head, 6)
head = push(head, 5)
head = push(head, 4)
head = push(head, 3)
head = push(head, 2)
head = push(head, 1)
     
print( "Given linked list: ", end = "")
printList(head)
         
evenOdd(head)
     
print("\nAfter rearrangement: ", end = "")
printList(head)
 
# This code is contributed by Arnab Kundu

C#

// C# program to segregate
// even and odd noeds in a
// linked list using deque
using System;
using System.Collections.Generic;
class GFG{
 
// Link list node
public class Node
{ 
  public int data;
  public Node next;
};
 
// UTILITY FUNCTIONS
// Push a node to linked list.
// Note that this function
// changes the head
static Node push(Node head_ref,
                 int new_data)
{
  // allocate node
  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 pochar
  // to the new node
  head_ref = new_node;
  return head_ref;
}
 
// Printing the linked list
static void printList(Node head)
{
  Node temp = head;
  while (temp != null)
  {
    Console.Write(" " + temp.data);
    temp = temp.next;
  }
}
 
// Function to rearrange even
// and odd elements in a linked
// list using deque
static void evenOdd(Node head)
{
  Node temp = head;
 
  // Declaring a Deque
  List d =
       new List();
 
  // Push all the elements of
  // linked list in to deque
  while (temp != null)
  {
    // if element is even push it
    // to front of the deque
    if (temp.data % 2 == 0)
      d.Insert(0, temp.data);
 
    else
       
      // else push at the
      // back of the deque
      d.Add(temp.data);
     
    // increase temp
    temp = temp.next;
  }
 
  temp = head;
 
  // Replace all elements of
  // the linked list with the
  // elements of Deque starting
  // from the first element
  while (d.Count != 0)
  {
    temp.data = d[0];
    d.RemoveAt(0);
    temp = temp.next;
  }
}
 
// Driver code
public static void Main(String[] args)
{
  Node head = null;
  head = push(head, 10);
  head = push(head, 9);
  head = push(head, 8);
  head = push(head, 7);
  head = push(head, 6);
  head = push(head, 5);
  head = push(head, 4);
  head = push(head, 3);
  head = push(head, 2);
  head = push(head, 1);
 
  Console.Write("Given linked list: ");
  printList(head);
 
  evenOdd(head);
 
  Console.Write("\nAfter rearrangement: ");
  printList(head);        
}
}
 
// This code is contributed by 29AjayKumar

Javascript

      // JavaScript program to segregate
      // even and odd noeds in a
      // linked list using deque
      // Link list node
      class Node {
        constructor() {
          this.data = 0;
          this.next = null;
        }
      }
 
      // UTILITY FUNCTIONS
      // Push a node to linked list.
      // Note that this function
      // changes the head
      function push(head_ref, new_data) {
        // allocate node
        var 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 pochar
        // to the new node
        head_ref = new_node;
        return head_ref;
      }
 
      // Printing the linked list
      function printList(head) {
        var temp = head;
        while (temp != null) {
          document.write(" " + temp.data);
          temp = temp.next;
        }
      }
 
      // Function to rearrange even
      // and odd elements in a linked
      // list using deque
      function evenOdd(head) {
        var temp = head;
 
        // Declaring a Deque
        var d = [];
 
        // Push all the elements of
        // linked list in to deque
        while (temp != null) {
          // if element is even push it
          // to front of the deque
          if (temp.data % 2 == 0) d.unshift(temp.data);
          // else push at the
          // back of the deque
          else d.push(temp.data);
 
          // increase temp
          temp = temp.next;
        }
 
        temp = head;
 
        // Replace all elements of
        // the linked list with the
        // elements of Deque starting
        // from the first element
        while (d.length != 0) {
          temp.data = d[0];
          d.shift();
          temp = temp.next;
        }
      }
 
      // Driver code
      var head = null;
      head = push(head, 10);
      head = push(head, 9);
      head = push(head, 8);
      head = push(head, 7);
      head = push(head, 6);
      head = push(head, 5);
      head = push(head, 4);
      head = push(head, 3);
      head = push(head, 2);
      head = push(head, 1);
 
      document.write("Given linked list: ");
      printList(head);
 
      evenOdd(head);
 
      document.write("<br>After rearrangement: ");
      printList(head);
       
      // This code is contributed by rdtank.
    

输出：

Given linked list: 1 2 3 4 5 6 7 8 9 10 
After rearrangement: 10 8 6 4 2 1 3 5 7 9

时间复杂度：O(N)
辅助空间：O(N)，其中 N 是链表中的节点总数。

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