Is Delete the Middle Node of a Linked List easy or hard?

The problem is classified as Medium difficulty on LeetCode. The logic is simple once you know the fast–slow pointer pattern, but candidates must correctly manage pointer updates and edge cases such as a single-node list.

Delete the Middle Node of a Linked List Python/Java solution

In Python or Java, maintain fast and slow pointers starting at the head and track the previous node of slow. Advance fast by two nodes and slow by one node until fast reaches the end. Then update prev.next to skip the slow node. The implementation runs in O(n) time and O(1) space.

How to solve Delete the Middle Node of a Linked List in O(n)?

Use the fast and slow pointer technique. Initialize slow, fast, and a previous pointer. Move fast two nodes at a time and slow one node at a time while tracking the previous node of slow. When fast reaches the end, delete the middle by setting prev.next to slow.next. The list is processed once, giving O(n) time and O(1) space.

What is the best approach for Delete the Middle Node of a Linked List?

The two-pointer (fast and slow pointer) approach is the best solution. It finds the middle node in a single traversal by moving the fast pointer two steps and the slow pointer one step at a time. When the fast pointer reaches the end, the slow pointer is at the middle. This method runs in O(n) time with O(1) extra space.

Is Delete the Middle Node of a Linked List asked at Google/Amazon/Meta?

Linked list pointer manipulation problems are common in interviews at companies like Amazon, Google, and Meta. Variants such as finding the middle node, removing the Nth node from the end, or deleting nodes during traversal frequently appear in technical screens.

What data structure is used in Delete the Middle Node of a Linked List?

The problem uses a singly linked list. Each node contains a value and a pointer to the next node. Solving it efficiently relies on pointer traversal techniques such as the fast–slow two-pointer method.

What is the time complexity of Delete the Middle Node of a Linked List?

The time complexity is O(n) because the algorithm must traverse the linked list to reach the middle. The two-pass method performs two linear scans, while the fast–slow pointer method completes the task in a single pass. Both approaches use O(1) additional space.

Description Hints 2 Solution Video 14:36

2095. Delete the Middle Node of a Linked List

Medium60.4% acceptance7 companies

You are given the head of a linked list. Delete the middle node, and return the head of the modified linked list.

The middle node of a linked list of size n is the ⌊n / 2⌋^th node from the start using 0-based indexing, where ⌊x⌋ denotes the largest integer less than or equal to x.

For n = 1, 2, 3, 4, and 5, the middle nodes are 0, 1, 1, 2, and 2, respectively.

Example 1:

Input: head = [1,3,4,7,1,2,6]
Output: [1,3,4,1,2,6]
Explanation:
The above figure represents the given linked list. The indices of the nodes are written below.
Since n = 7, node 3 with value 7 is the middle node, which is marked in red.
We return the new list after removing this node.

Example 2:

Input: head = [1,2,3,4]
Output: [1,2,4]
Explanation:
The above figure represents the given linked list.
For n = 4, node 2 with value 3 is the middle node, which is marked in red.

Example 3:

Input: head = [2,1]
Output: [2]
Explanation:
The above figure represents the given linked list.
For n = 2, node 1 with value 1 is the middle node, which is marked in red.
Node 0 with value 2 is the only node remaining after removing node 1.

Constraints:

The number of nodes in the list is in the range [1, 10⁵].
1 <= Node.val <= 10⁵

Asked at 7 companies

Google

TCS Microsoft Bloomberg Goldman Sachs Amazon Meta

Topics

Linked List Two Pointers

Hints open one at a time

Hint 1

If a point with a speed s moves n units in a given time, a point with speed 2 * s will move 2 * n units at the same time. Can you use this to find the middle node of a linked list?

Hint 2

If you are given the middle node, the node before it, and the node after it, how can you modify the linked list?

14:36

Still stuck?Read 3 approaches, or watch a walkthrough.

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