数据结构:使用栈对链表元素位序进行反转

给定一个链表,业务需求:使用栈将链表中元素的次序进行反转。

输入 : List = 3 -> 2 -> 1
输出 : 1 -> 2 -> 3

输入 : 9 -> 7 -> 4 -> 2
输出 : 2 -> 4 -> 7 -> 9 

算法过程：算法复杂度:O(n)1、遍历列表，将所有节点推到栈上。2、遍历栈，并依次从栈顶弹出元素用相反顺序存储。java代码：

// Java program to reverse linked list
// using stack
import java.util.*;
class GfG
{ 

/* Link list node */
static class Node
{
    int data;
    Node next;
}
static Node head = null; 

/* Given a reference (pointer to pointer) to
the head of a list and an int, push a new
node on the front of the list. */
static void push( int new_data)
{
    Node new_node = new Node(); 

    new_node.data = new_data;
    new_node.next = (head);
    (head) = new_node;
} 

// Function to reverse linked list
static Node reverseList(Node head)
{
    // Stack to store elements of list
    Stack<Node > stk = new Stack<Node> (); 

    // Push the elements of list to stack
    Node ptr = head;
    while (ptr.next != null)
    {
        stk.push(ptr);
        ptr = ptr.next;
    } 

    // Pop from stack and replace
    // current nodes value‘
    head = ptr;
    while (!stk.isEmpty())
    {
        ptr.next = stk.peek();
        ptr = ptr.next;
        stk.pop();
    }
    ptr.next = null; 

    return head;
} 

// Function to print the Linked list
static void printList(Node head)
{
    while (head != null)
    {
        System.out.print(head.data + " ");
        head = head.next;
    }
} 

// Driver Code
public static void main(String[] args)
{
    /* Start with the empty list */
    //Node head = null; 

    /* Use push() to construct below list
    1->2->3->4->5 */
    push( 5);
    push( 4);
    push( 3);
    push( 2);
    push( 1); 

    head = reverseList(head); 

    printList(head);
}
} 

// This code is contributed by Prerna Saini. 

c#代码

// C# program to reverse linked list
// using stack
using System;
using System.Collections.Generic; 

class GfG
{ 

/* Link list node */
public class Node
{
    public int data;
    public Node next;
}
static Node head = null; 

/* Given a reference (pointer to pointer) to
the head of a list and an int, push a new
node on the front of the list. */
static void push( int new_data)
{
    Node new_node = new Node(); 

    new_node.data = new_data;
    new_node.next = (head);
    (head) = new_node;
} 

// Function to reverse linked list
static Node reverseList(Node head)
{
    // Stack to store elements of list
    Stack<Node > stk = new Stack<Node> (); 

    // Push the elements of list to stack
    Node ptr = head;
    while (ptr.next != null)
    {
        stk.Push(ptr);
        ptr = ptr.next;
    } 

    // Pop from stack and replace
    // current nodes value‘
    head = ptr;
    while (stk.Count != 0)
    {
        ptr.next = stk.Peek();
        ptr = ptr.next;
        stk.Pop();
    }
    ptr.next = null; 

    return head;
} 

// Function to print the Linked list
static void printList(Node head)
{
    while (head != null)
    {
        Console.Write(head.data + " ");
        head = head.next;
    }
} 

// Driver Code
public static void Main(String[] args)
{
    /* Start with the empty list */
    //Node head = null; 

    /* Use push() to construct below list
    1->2->3->4->5 */
    push( 5);
    push( 4);
    push( 3);
    push( 2);
    push( 1); 

    head = reverseList(head); 

    printList(head);
}
} 

// This code contributed by Rajput-Ji 

算法2(迭代)：

时间复杂度:O(1)

// Iterative C program to reverse a linked list
#include <stdio.h>
#include <stdlib.h>

/* Linked list node */
struct Node
{
    int data;
    struct Node* next;
};

//function to reverse the linked list
static void reverse(struct Node** head_ref)
{
    struct Node* prev = NULL;
    struct Node* current = *head_ref;
    struct Node* next = NULL;

    while(current != NULL)
    {
        //Store next
        next = current->next;

        //Move pointers one position ahead.
        prev = current;

        current = next;
    }
    *head_ref = prev;
}

/* function to push a node */
void push(struct Node** head_ref, int new_data)
{
    struct Node* new_node = (struct Node*)malloc(sizeof(struct Node));
    new_node->data = new_data;
    new_node->next =(*head_ref);
    (*head_ref) = new_node;
}

/* function to print linked list */
void printList(struct Node* head)
{
    struct Node* temp = head;
    while( temp != NULL)
    {
        printf("%d ", temp->data);
        temp = temp->next;
    }
    printf("\n");
}

/* Driver program to test above function */
int main()
{
    /* Start with the empty list */
    struct Node* head = NULL;

    push(&head, 20);
    push(&head, 4);
    push(&head, 15);
    push(&head, 85);

    printf("Given linked list\n");
    printList(head);

    reverse(&head);

    printf("Reversed Linked List\n");
    printList(head);
}

文章来源：https://www.geeksforgeeks.org/program-to-reverse-a-linked-list-using-stack/

原文地址：https://www.cnblogs.com/passedbylove/p/11442606.html