To reverse a doubly linked list, you can follow these steps:

1. Initialize three pointers, `current` pointing to the head of the list, and `prev` and `next` as `null`.

2. Traverse through the list until `current` is not `null`.

3. For each node, do the following:
- Set `next` as `current.next`.
- Change the next of `current` to `prev` (This is where actual reversing happens).
- Change the prev of `current` to `next` (This is where actual reversing happens).
- Move `prev` and `current` one step forward.

4. Set `prev` as the new head of the list.

Here is a Python code snippet that implements the above steps:

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

def reverse(head):
temp = None
current = head

# Swap next and prev for all nodes of doubly linked list
while current is not None:
temp = current.prev
current.prev = current.next
current.next = temp
current = current.prev

# Before changing head, check for the cases like empty list and list with only one node
if temp is not None:
head = temp.prev

return head
```

In the given example, the list before reversal is 1 - 2 - 3. After reversing, the list becomes 3 - 2 - 1.

Question

To reverse a doubly linked list, you can follow these steps:

1. Initialize three pointers, `current` pointing to the head of the list, and `prev` and `next` as `null`.

2. Traverse through the list until `current` is not `null`.

3. For each node, do the following:
   - Set `next` as `current.next`.
   - Change the next of `current` to `prev` (This is where actual reversing happens).
   - Change the prev of `current` to `next` (This is where actual reversing happens).
   - Move `prev` and `current` one step forward.

4. Set `prev` as the new head of the list.

Here is a Python code snippet that implements the above steps:

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

def reverse(head):
    temp = None
    current = head

# Swap next and prev for all nodes of doubly linked list
    while current is not None:
        temp = current.prev
        current.prev = current.next
        current.next = temp
        current = current.prev

# Before changing head, check for the cases like empty list and list with only one node
    if temp is not None:
        head = temp.prev

return head
```

In the given example, the list before reversal is 1 -> 2 -> 3. After reversing, the list becomes 3 -> 2 -> 1.

Knowee AI · Accepted Answer