24.从单向链表中删除指定值的节点

题目描述

输入一个单向链表和一个节点的值，从单向链表中删除等于该值的节点，删除后如果链表中无节点则返回空指针。

链表结点定义如下：

struct ListNode

{

      int       m_nKey;

      ListNode* m_pNext;

};

详细描述：

本题为考察链表的插入和删除知识。

链表的值不能重复

构造过程，例如

1 -> 2

3 -> 2

5 -> 1

4 -> 5

7 -> 2

最后的链表的顺序为 2 7 3 1 5 4 

删除 结点 2 

则结果为 7 3 1 5 4 

import java.util.Scanner;import java.util.Stack; public class Main {    public static void main(String[] args) {        Scanner in = new Scanner(System.in);        while(in.hasNext())        {            //输入节点数            int nodeNum = in.nextInt();            //输入头节点的值            int headVal = in.nextInt();            //构造头节点            Node pHead = new Node(headVal);            for(int i = 0;i < nodeNum - 1;i ++)            {                //插入节点值                int nextVal = in.nextInt();                //前一节点值                int preVal = in.nextInt();                //插入节点                insert(pHead,preVal,nextVal);            }            int deleteVal = in.nextInt();            pHead = removeNode(pHead, deleteVal);            while(pHead.next != null)            {                System.out.print(pHead.val + " ");                pHead = pHead.next;            }            System.out.println(pHead.val + " ");        }    }    /*     参数 pHead 头节点     preVal 上一节点值     nextVal 插入节点值     */    public static void insert(Node pHead,int preVal,int nextVal)    {        Node pNext = new Node(nextVal);        Node pCurrent = pHead;        while(pCurrent != null)        {            if(pCurrent.val == preVal)            {                pNext.next = pCurrent.next;                pCurrent.next = pNext;                break;            }            pCurrent = pCurrent.next;        }    }    public static Node removeNode(Node pHead,int val)    {        Stack<Node> stack = new Stack<Node>();        Node preNode = pHead;        while(pHead != null)        {            if(pHead.val != val)            {                stack.push(pHead);                            }             pHead = pHead.next;        }        while(!stack.isEmpty())        {            stack.peek().next = pHead;            pHead = stack.pop();        }        return pHead;    }}class Node{    public int val;    public Node next;    public Node(int val)    {        this.val = val;    }}