Which of the following is a correct method to reverse a doubly linked list?Swap the next and prev pointers of all nodes.Replace all nodes with their corresponding mirror nodes.Swap the data of all nodes.Create a new list and copy nodes in reverse order.
Question
Which of the following is a correct method to reverse a doubly linked list?Swap the next and prev pointers of all nodes.Replace all nodes with their corresponding mirror nodes.Swap the data of all nodes.Create a new list and copy nodes in reverse order.
Solution 1
The correct method to reverse a doubly linked list is to swap the next and prev pointers of all nodes.
Here is a step-by-step guide on how to do it:
-
Initialize three pointers,
current,next, andprev. Setcurrentto the head of the doubly linked list andprevtonull. -
Loop through the list until
currentisnull. In each iteration, perform the following steps:a. Set
nextto thenextnode ofcurrent.b. Set the
nextnode ofcurrenttoprev. This is where the actual reversing happens.c. Set the
prevnode ofcurrenttonext. This step is necessary to maintain the doubly linked list structure after reversing.d. Move
prevandcurrentone step forward. Setprevtocurrentandcurrenttonext. -
Once the loop is over, set the head of the list to
prevbecausecurrentis nownull.
This method effectively reverses the doubly linked list by swapping the next and prev pointers of all nodes.
Solution 2
The correct method to reverse a doubly linked list is to swap the next and prev pointers of all nodes. Here's a step-by-step guide on how to do it:
- Initialize three pointers,
current,next, andprev. - Set
currentto the head of the doubly linked list. - Loop through the list until
currentis NULL.- Inside the loop, set
nextto thenextnode ofcurrent. - Then, swap the
nextandprevpointers ofcurrent. - Move
prevandcurrentone step forward. Setprevtocurrentandcurrenttonext.
- Inside the loop, set
- Once the loop is over, set the
headof the list toprevas it will be the new head of the reversed list.
This method works because it iteratively swaps the next and prev pointers of each node, effectively reversing the direction of the list. The other methods mentioned in the question are not correct ways to reverse a doubly linked list.
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