如果当前节点在单向链表中为零，则更新相邻节点

给定一个链表。任务是如果当前节点为0，则将节点的上一个和下一个节点的值更改为0。
例子：

Input :  2->3->4->5->0->9->0->9->NULL
Output : 2->3->4->0->0->0->0->0->NULL

Input : 0->2->3->4->0->0->NULL
Output : 0->0->3->0->0->0->NULL

算法：

1. 第一步是创建两个指针prev和curr 。
   prev将指向前一个节点，而curr将指向当前节点。使用prev的原因是我们不能在单链表中回溯。
2. 如果第一个节点为0，则检查下一个节点是否为0
   • 如果是，则跳过
   • 否则将下一个节点更改为-1 。
3. 开始遍历列表的节点。
   • 如果当前节点为0且变量temp为0则
     • 将上一个节点设置为-1 。
     • 将临时变量设置为1 。
   • 如果临时值为1且当前节点数据不是1，则将当前节点设置为-1
4. 重复步骤 3，直到到达列表末尾。
5. 遍历列表并将值为-1的节点更改为0 。

使用temp和-1 的原因是，如果我们直接将下一个节点更改为0 ，那么这可能会导致将下一个节点之后的节点更改为0 ，结果整个列表可能会更改为0 。
下面是上述方法的实现：

C++

// C++ program to update the adjacent
// nodes in a linked list
 
#include 
using namespace std;
 
// A linked list node
struct Node {
    int data;
    struct Node* next;
};
 
// Utility function to create a new Node
Node* newNode(int data)
{
    Node* temp = new Node;
    temp->data = data;
    temp->next = NULL;
 
    return temp;
}
 
// Function to display the linked list
void printList(Node* node)
{
    // iterate until end of the list is reached
    while (node != NULL) {
        cout << node->data << " ";
 
        node = node->next;
    }
}
 
// Function to update the adjacent
// nodes to zero
void updateAdjacent(Node* head)
{
    // Pointer to point to
    // the previous node
    Node* prev = head;
 
    // Pointer to the
    // current node
    Node* curr = head->next;
 
    // If the first node is zero and the
    // second node is not zero then change
    // the value to -1
    if (prev->data == 0 && curr->data != 0)
        curr->data = -1;
 
    // Temp variable to denote if the
    // current node is zero then the next
    // node will be changed to zero
    int temp = 0;
 
    while (curr != NULL) {
 
        // if the temp variable is 1 and
        // current data is not zero
        if (temp == 1 && curr->data != 0) {
 
            // change the data to -1
            curr->data = -1;
            temp = 0;
        }
 
        // if the data is zero
        if (curr->data == 0) {
 
            // set the temp variable to 1
            temp = 1;
 
            // set the previous node data to -1
            prev->data = -1;
        }
 
        curr = curr->next;
        prev = prev->next;
    }
 
    curr = head;
 
    // change all the nodes with -1 to 0
    while (curr != NULL) {
        if (curr->data == -1)
            curr->data = 0;
 
        curr = curr->next;
    }
}
 
// Driver code
int main()
{
    // creating the linked list
    Node* head = newNode(2);
    head->next = newNode(3);
    head->next->next = newNode(4);
    head->next->next->next = newNode(5);
    head->next->next->next->next = newNode(0);
    head->next->next->next->next->next = newNode(9);
    head->next->next->next->next->next->next = newNode(0);
    head->next->next->next->next->next->next->next = newNode(9);
 
    updateAdjacent(head);
 
    printList(head);
 
    return 0;
}

Java

// Java program to update the adjacent
// nodes in a linked list
class GFG
{
 
// A linked list node
static class Node
{
    int data;
    Node next;
}
 
// Utility function to create a new Node
static Node newNode(int data)
{
    Node temp = new Node();
    temp.data = data;
    temp.next = null;
 
    return temp;
}
 
// Function to display the linked list
static void printList(Node node)
{
    // iterate until end of the list is reached
    while (node != null)
    {
        System.out.print(node.data + " ");
 
        node = node.next;
    }
}
 
// Function to update the adjacent
// nodes to zero
static void updateAdjacent(Node head)
{
    // Pointer to point to
    // the previous node
    Node prev = head;
 
    // Pointer to the
    // current node
    Node curr = head.next;
 
    // If the first node is zero and the
    // second node is not zero then change
    // the value to -1
    if (prev.data == 0 && curr.data != 0)
        curr.data = -1;
 
    // Temp variable to denote if the
    // current node is zero then the next
    // node will be changed to zero
    int temp = 0;
 
    while (curr != null)
    {
 
        // if the temp variable is 1 and
        // current data is not zero
        if (temp == 1 && curr.data != 0)
        {
 
            // change the data to -1
            curr.data = -1;
            temp = 0;
        }
 
        // if the data is zero
        if (curr.data == 0)
        {
 
            // set the temp variable to 1
            temp = 1;
 
            // set the previous node data to -1
            prev.data = -1;
        }
 
        curr = curr.next;
        prev = prev.next;
    }
 
    curr = head;
 
    // change all the nodes with -1 to 0
    while (curr != null)
    {
        if (curr.data == -1)
            curr.data = 0;
 
        curr = curr.next;
    }
}
 
// Driver code
public static void main(String[] args)
{
    // creating the linked list
    Node head = newNode(2);
    head.next = newNode(3);
    head.next.next = newNode(4);
    head.next.next.next = newNode(5);
    head.next.next.next.next = newNode(0);
    head.next.next.next.next.next = newNode(9);
    head.next.next.next.next.next.next = newNode(0);
    head.next.next.next.next.next.next.next = newNode(9);
 
    updateAdjacent(head);
 
    printList(head);
}
}
 
/* This code contributed by PrinciRaj1992 */

Python3

# Python3 program to update the adjacent
# nodes in a linked list
 
# A linked list node
class Node:
     
    def __init__(self, data):
        self.data = data
        self.next = None
 
# Function to display the linked list
def printList(node):
 
    # iterate until end of the
    # list is reached
    while node != None:
        print(node.data, end = " ")
 
        node = node.next
 
# Function to update the adjacent
# nodes to zero
def updateAdjacent(head):
 
    # Pointer to point to
    # the previous node
    prev = head
 
    # Pointer to the
    # current node
    curr = head.next
 
    # If the first node is zero and the
    # second node is not zero then change
    # the value to -1
    if prev.data == 0 and curr.data != 0:
        curr.data = -1
 
    # Temp variable to denote if the
    # current node is zero then the next
    # node will be changed to zero
    temp = 0
 
    while curr != None:
 
        # if the temp variable is 1 and
        # current data is not zero
        if temp == 1 and curr.data != 0:
 
            # change the data to -1
            curr.data = -1
            temp = 0
 
        # if the data is zero
        if curr.data == 0:
 
            # set the temp variable to 1
            temp = 1
 
            # set the previous node data to -1
            prev.data = -1
         
        curr = curr.next
        prev = prev.next
     
    curr = head
 
    # change all the nodes with -1 to 0
    while curr != None:
        if curr.data == -1:
            curr.data = 0
 
        curr = curr.next
     
# Driver Code
if __name__ == "__main__":
 
    # creating the linked list
    head = Node(2)
    head.next = Node(3)
    head.next.next = Node(4)
    head.next.next.next = Node(5)
    head.next.next.next.next = Node(0)
    head.next.next.next.next.next = Node(9)
    head.next.next.next.next.next.next = Node(0)
    head.next.next.next.next.next.next.next = Node(9)
 
    updateAdjacent(head)
 
    printList(head)
 
# This code is contributed by Rituraj Jain

C#

// C# program to update the adjacent
// nodes in a linked list
using System;
 
class GFG
{
 
// A linked list node
public class Node
{
    public int data;
    public Node next;
}
 
// Utility function to create a new Node
static Node newNode(int data)
{
    Node temp = new Node();
    temp.data = data;
    temp.next = null;
 
    return temp;
}
 
// Function to display the linked list
static void printList(Node node)
{
    // iterate until end of the list is reached
    while (node != null)
    {
        Console.Write(node.data + " ");
 
        node = node.next;
    }
}
 
// Function to update the adjacent
// nodes to zero
static void updateAdjacent(Node head)
{
    // Pointer to point to
    // the previous node
    Node prev = head;
 
    // Pointer to the
    // current node
    Node curr = head.next;
 
    // If the first node is zero and the
    // second node is not zero then change
    // the value to -1
    if (prev.data == 0 && curr.data != 0)
        curr.data = -1;
 
    // Temp variable to denote if the
    // current node is zero then the next
    // node will be changed to zero
    int temp = 0;
 
    while (curr != null)
    {
 
        // if the temp variable is 1 and
        // current data is not zero
        if (temp == 1 && curr.data != 0)
        {
 
            // change the data to -1
            curr.data = -1;
            temp = 0;
        }
 
        // if the data is zero
        if (curr.data == 0)
        {
 
            // set the temp variable to 1
            temp = 1;
 
            // set the previous node data to -1
            prev.data = -1;
        }
 
        curr = curr.next;
        prev = prev.next;
    }
 
    curr = head;
 
    // change all the nodes with -1 to 0
    while (curr != null)
    {
        if (curr.data == -1)
            curr.data = 0;
 
        curr = curr.next;
    }
}
 
// Driver code
public static void Main(String[] args)
{
    // creating the linked list
    Node head = newNode(2);
    head.next = newNode(3);
    head.next.next = newNode(4);
    head.next.next.next = newNode(5);
    head.next.next.next.next = newNode(0);
    head.next.next.next.next.next = newNode(9);
    head.next.next.next.next.next.next = newNode(0);
    head.next.next.next.next.next.next.next = newNode(9);
 
    updateAdjacent(head);
 
    printList(head);
}
}
 
// This code contributed by Rajput-Ji

Javascript

// javascript program to update the adjacent
// nodes in a linked list    // A linked list node
     class Node {
 
            constructor(val) {
                this.data = val;
                this.next = null;
            }
         
    }
 
    // Utility function to create a new Node
    function newNode(data) {
var temp = new Node();
        temp.data = data;
        temp.next = null;
 
        return temp;
    }
 
    // Function to display the linked list
    function printList(node) {
        // iterate until end of the list is reached
        while (node != null) {
            document.write(node.data + " ");
 
            node = node.next;
        }
    }
 
    // Function to update the adjacent
    // nodes to zero
    function updateAdjacent(head) {
        // Pointer to povar to
        // the previous node
var prev = head;
 
        // Pointer to the
        // current node
var curr = head.next;
 
        // If the first node is zero and the
        // second node is not zero then change
        // the value to -1
        if (prev.data == 0 && curr.data != 0)
            curr.data = -1;
 
        // Temp variable to denote if the
        // current node is zero then the next
        // node will be changed to zero
        var temp = 0;
 
        while (curr != null) {
 
            // if the temp variable is 1 and
            // current data is not zero
            if (temp == 1 && curr.data != 0) {
 
                // change the data to -1
                curr.data = -1;
                temp = 0;
            }
 
            // if the data is zero
            if (curr.data == 0) {
 
                // set the temp variable to 1
                temp = 1;
 
                // set the previous node data to -1
                prev.data = -1;
            }
 
            curr = curr.next;
            prev = prev.next;
        }
 
        curr = head;
 
        // change all the nodes with -1 to 0
        while (curr != null) {
            if (curr.data == -1)
                curr.data = 0;
 
            curr = curr.next;
        }
    }
 
    // Driver code
     
        // creating the linked list
var head = newNode(2);
        head.next = newNode(3);
        head.next.next = newNode(4);
        head.next.next.next = newNode(5);
        head.next.next.next.next = newNode(0);
        head.next.next.next.next.next = newNode(9);
        head.next.next.next.next.next.next = newNode(0);
        head.next.next.next.next.next.next.next = newNode(9);
 
        updateAdjacent(head);
 
        printList(head);
 
// This code is contributed by todaysgaurav

输出：

2 3 4 0 0 0 0 0

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