237. Delete Node in a Linked List (Easy)

https://leetcode.com/problems/delete-node-in-a-linked-list/

Write a function to delete a node (except the tail) in a singly linked list, given only access to that node.

Given linked list -- head = [4,5,1,9], which looks like following:

Example 1:

Input: head = [4,5,1,9], node = 5
Output: [4,1,9]
Explanation: You are given the second node with value 5, the linked list should become 4 -> 1 -> 9 after calling your function.

Example 2:

Input: head = [4,5,1,9], node = 1
Output: [4,5,9]
Explanation: You are given the third node with value 1, the linked list should become 4 -> 5 -> 9 after calling your function.

Note:

• The linked list will have at least two elements.
• All of the nodes' values will be unique.
• The given node will not be the tail and it will always be a valid node of the linked list.
• Do not return anything from your function.

Solutions

class Solution {
    public void deleteNode(ListNode node) {
        ListNode p1 = node;

        // as problem described, p2 should never be null
        ListNode p2 = p1.next;

        // a->b->c->p1->p2

        // break until p2.next == null, not p2 == null
        while (p2.next != null) {
            p1.val = p2.val;

            p1 = p2;
            p2 = p2.next;
        }

        // Once get out from the loop, p2 != null, we need to move p2's
        // value forward to p1
        p1.val = p2.val;
        p1.next = null;
    }
}

Incorrect Solutions

References