原文：
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
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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