使用递归交替打印链表节点
原文：https://www.geeksforgeeks.org/print-alternate-nodes-linked-list-using-recursion/
给定一个链表，请交替打印此链表节点。
示例：
Input : 1 -> 2 -> 3 -> 4 -> 5 -> 6 -> 7 -> 8 -> 9 -> 10
Output : 1 -> 3 -> 5 -> 7 -> 9
Input : 10 -> 9
Output : 10
递归方法：
-
初始化静态变量（例如标记）
-
如果标记为奇数，则打印节点
-
将头和标记加 1，然后递归返回下一个节点。
C++
// CPP code to print alternate nodes
// of a linked list using recursion
#include <bits/stdc++.h>
using namespace std;
// A linked list node
struct Node {
int data;
struct Node* next;
};
// Inserting node at the beginning
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 alternate nodes of linked list.
// The boolean flag isOdd is used to find if the current
// node is even or odd.
void printAlternate(struct Node* node, bool isOdd=true)
{
if (node == NULL)
return;
if (isOdd == true)
cout << node->data << " ";
printAlternate(node->next, !isOdd);
}
// Driver code
int main()
{
// Start with the empty list
struct Node* head = NULL;
// construct below list
// 1->2->3->4->5->6->7->8->9->10
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);
printAlternate(head);
return 0;
}
Java
// Java code to print alternate nodes
// of a linked list using recursion
class GFG
{
// A linked list node
static class Node
{
int data;
Node next;
};
// Inserting node at the beginning
static Node push( Node head_ref, int new_data)
{
Node new_node = new Node();
new_node.data = new_data;
new_node.next = (head_ref);
(head_ref) = new_node;
return head_ref;
}
// Function to print alternate nodes of linked list.
// The boolean flag isOdd is used to find if the current
// node is even or odd.
static void printAlternate( Node node, boolean isOdd)
{
if (node == null)
return;
if (isOdd == true)
System.out.print( node.data + " ");
printAlternate(node.next, !isOdd);
}
// Driver code
public static void main(String args[])
{
// Start with the empty list
Node head = null;
// con below list
// 1.2.3.4.5.6.7.8.9.10
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);
printAlternate(head,true);
}
}
// This code is contributed by Arnab Kundu
Python3
# Python3 code to print alternate nodes
# of a linked list using recursion
# A linked list node
class Node:
def __init__(self, data):
self.data = data
self.next = None
# Inserting node at the beginning
def push( head_ref, new_data):
new_node = Node(new_data);
new_node.data = new_data;
new_node.next = head_ref;
head_ref = new_node;
return head_ref;
# Function to print alternate nodes of
# linked list. The boolean flag isOdd
# is used to find if the current node
# is even or odd.
def printAlternate( node, isOdd):
if (node == None):
return;
if (isOdd == True):
print( node.data, end = " ");
if (isOdd == True):
isOdd = False;
else:
isOdd = True;
printAlternate(node.next, isOdd);
# Driver code
# Start with the empty list
head = None;
# con below list
# 1->2->3->4->5->6->7->8->9->10
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);
printAlternate(head, True);
# This code is contributed by 29AjayKumar
C
// C# code to print alternate nodes
// of a linked list using recursion
using System;
class GFG
{
// A linked list node
public class Node
{
public int data;
public Node next;
};
// Inserting node at the beginning
static Node push( Node head_ref, int new_data)
{
Node new_node = new Node();
new_node.data = new_data;
new_node.next = (head_ref);
(head_ref) = new_node;
return head_ref;
}
// Function to print alternate nodes of linked list.
// The boolean flag isOdd is used to find if the current
// node is even or odd.
static void printAlternate( Node node, bool isOdd)
{
if (node == null)
return;
if (isOdd == true)
Console.Write( node.data + " ");
printAlternate(node.next, !isOdd);
}
// Driver code
public static void Main(String []args)
{
// Start with the empty list
Node head = null;
// con below list
// 1.2.3.4.5.6.7.8.9.10
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);
printAlternate(head,true);
}
}
// This code has been contributed by 29AjayKumar
输出：
1 3 5 7 9
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