Is Convert Doubly Linked List to Array I easy or hard?

Convert Doubly Linked List to Array I is considered an Easy problem. It mainly tests basic understanding of linked list traversal and how to transfer node values into a sequential array structure.

Convert Doubly Linked List to Array I Python/Java solution

The Python solution typically uses a list and appends values while traversing the nodes. In Java, an ArrayList is commonly used during traversal and then returned as an array if required. Both implementations follow the same O(n) traversal logic.

How to solve Convert Doubly Linked List to Array I in O(n)?

Traverse the list starting from the head and follow the next pointers until you reach the end. For every node visited, push its value into an array or list. Since each node is processed once, the algorithm runs in O(n) time with O(n) additional space.

What is the best approach for Convert Doubly Linked List to Array I?

Direct traversal is the best approach. Start from the head node and iterate through the doubly linked list using the next pointer, appending each node value to an array. This processes every node exactly once, resulting in O(n) time and O(n) space.

Is Convert Doubly Linked List to Array I asked at Google/Amazon/Meta?

Problems involving linked list traversal and conversions appear frequently in interviews at companies like Amazon, Google, and Meta. While this exact problem may vary, the underlying concept of iterating through linked list nodes and building another structure is a common interview pattern.

What data structure is used in Convert Doubly Linked List to Array I?

The problem involves two core data structures: a doubly linked list for the input and an array for the output. The algorithm simply walks through the linked list and copies each node value into the array in order.

What is the time complexity of Convert Doubly Linked List to Array I?

The optimal solution runs in O(n) time because each node in the doubly linked list is visited exactly once during traversal. The resulting array stores all node values, so the space complexity is O(n).

Description Solution Video 2:00

3263. Convert Doubly Linked List to Array I

Easy95.0% acceptancePremium elsewhere, free here

You are given the head of a doubly linked list, which contains nodes that have a next pointer and a previous pointer.

Return an integer array which contains the elements of the linked list in order.

Example 1:

Input: head = [1,2,3,4,3,2,1]

Output: [1,2,3,4,3,2,1]

Example 2:

Input: head = [2,2,2,2,2]

Output: [2,2,2,2,2]

Example 3:

Input: head = [3,2,3,2,3,2]

Output: [3,2,3,2,3,2]

Constraints:

The number of nodes in the given list is in the range [1, 50].
1 <= Node.val <= 50

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3263. Convert Doubly Linked List to Array I

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