The problem is asking to print alternate elements of a linked list from the start to the end and then from the end to the start.

Here is a step by step solution in Python:

1. First, we need to create a linked list from the given input. We can create a Node class and a LinkedList class for this purpose.

```python
class Node:
def __init__(self, data=None):
self.data = data
self.next = None

class LinkedList:
def __init__(self):
self.head = None
```

2. Next, we need to add a method in the LinkedList class to add elements to the linked list.

```python
def append(self, data):
if not self.head:
self.head = Node(data)
else:
curr = self.head
while curr.next:
curr = curr.next
curr.next = Node(data)
```

3. Now, we need to add a method to print alternate elements from the start to the end. We can do this by traversing the linked list and printing the data of every second node.

```python
def print_alternate_start_to_end(self):
curr = self.head
count = 0
while curr:
if count % 2 == 0:
print(curr.data, end=' ')
curr = curr.next
count += 1
```

4. Similarly, we need to add a method to print alternate elements from the end to the start. We can do this by first reversing the linked list and then printing the data of every second node.

```python
def print_alternate_end_to_start(self):
self.reverse()
self.print_alternate_start_to_end()

def reverse(self):
prev = None
curr = self.head
while curr:
next_node = curr.next
curr.next = prev
prev = curr
curr = next_node
self.head = prev
```

5. Finally, we can create a linked list from the input, call the print_alternate_start_to_end method, and then call the print_alternate_end_to_start method.

```python
ll = LinkedList()
for i in input().split():
ll.append(int(i))
ll.print_alternate_start_to_end()
print()
ll.print_alternate_end_to_start()
```

This will print the alternate elements of the linked list from the start to the end and then from the end to the start.

Question

The problem is asking to print alternate elements of a linked list from the start to the end and then from the end to the start.

Here is a step by step solution in Python:

1. First, we need to create a linked list from the given input. We can create a Node class and a LinkedList class for this purpose.

```python
class Node:
    def __init__(self, data=None):
        self.data = data
        self.next = None

class LinkedList:
    def __init__(self):
        self.head = None
```

2. Next, we need to add a method in the LinkedList class to add elements to the linked list.

```python
def append(self, data):
    if not self.head:
        self.head = Node(data)
    else:
        curr = self.head
        while curr.next:
            curr = curr.next
        curr.next = Node(data)
```

3. Now, we need to add a method to print alternate elements from the start to the end. We can do this by traversing the linked list and printing the data of every second node.

```python
def print_alternate_start_to_end(self):
    curr = self.head
    count = 0
    while curr:
        if count % 2 == 0:
            print(curr.data, end=' ')
        curr = curr.next
        count += 1
```

4. Similarly, we need to add a method to print alternate elements from the end to the start. We can do this by first reversing the linked list and then printing the data of every second node.

```python
def print_alternate_end_to_start(self):
    self.reverse()
    self.print_alternate_start_to_end()

def reverse(self):
    prev = None
    curr = self.head
    while curr:
        next_node = curr.next
        curr.next = prev
        prev = curr
        curr = next_node
    self.head = prev
```

5. Finally, we can create a linked list from the input, call the print_alternate_start_to_end method, and then call the print_alternate_end_to_start method.

```python
ll = LinkedList()
for i in input().split():
    ll.append(int(i))
ll.print_alternate_start_to_end()
print()
ll.print_alternate_end_to_start()
```

This will print the alternate elements of the linked list from the start to the end and then from the end to the start.

Knowee AI · Accepted Answer