Delete the Middle Node of a Linked List — LeetCode 2095 Python Solution

The problem

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

Example

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.

Python solution

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def deleteMiddle(self, head: Optional[ListNode]) -> Optional[ListNode]:
        dummy = ListNode(next=head)
        slow, fast = dummy, head
        while fast and fast.next:
            slow = slow.next
            fast = fast.next.next
        slow.next = slow.next.next
        return dummy.next

Complexity

Pattern: Linked List

Rewire pointers in place, with a dummy head and a saved next to keep it safe. LeetCode 2095. Delete the Middle Node of a Linked List is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Linked List.

The linked list guide has the Python template for the pattern and the 75 LeetCode problems that use it.

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