Delete Alternate Nodes

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Time: O(n)

Space: O(1)

Problem Overview

Delete every alternate node in linked list (keep first, delete second, keep third, etc.).

Intuition

Delete every alternate node in linked list (keep first, delete second, keep third, etc.).

Algorithm

1Traverse: curr = head. While curr and curr.next: curr.next = curr.next.next. curr = curr.next.

Common Pitfalls

• Simple pointer manipulation. Ensure the "next" link skips the deleted node cleanly.

Delete Alternate Nodes.java

Java

// Approach: Traverse the list and skip every other node by updating next pointers.
// Time: O(n) Space: O(1)
class Solution {
    public void deleteAlt(Node head) {
        Node prev = null;
        Node temp = head;
        int cnt = 0;
        while (temp != null) {
            cnt++;
            if (cnt % 2 == 0) {
                prev.next = temp.next;
            }
            prev = temp;
            temp = temp.next;
        }
    }
}

class Node {
    int data;
    Node next;

    public Node(int data) {
        this.data = data;
    }
}

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