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# Linked List Delete Middle Node

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. ![image](https://github.com/VikashChauhan51/algorithms/assets/14816038/b077d948-575b-4c08-93ec-597ad0997c9a)

### Solution

```csharp
/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     public int val;
 *     public ListNode next;
 *     public ListNode(int val=0, ListNode next=null) {
 *         this.val = val;
 *         this.next = next;
 *     }
 * }
 */
public class Solution {
    public ListNode DeleteMiddle(ListNode head) {
        
         if (head.next == null) return null;

        ListNode fast = head;
        ListNode slow = new ListNode(0, head);
        while (fast != null && fast.next != null)
        {
            fast = fast.next.next;
            slow = slow.next;
        }
        slow.next = slow.next.next;
        return head;
    }
}
```

The time complexity of the `DeleteMiddle` algorithm is **O(n)**, where **n** is the number of nodes in the linked list. This is because each node in the list is visited exactly once.

The space complexity of the algorithm is **O(1)**. This is because the algorithm only uses a constant amount of space to store the pointers (`fast`, `slow`), regardless of the size of the input linked list. The algorithm modifies the input linked list in-place and does not use any additional data structures whose size depends on the input. Hence, the space complexity is constant.