Problem

Problem_Link

Solutions (time, space)

O(1), O(1)

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
class Solution {
    public void deleteNode(ListNode node) {
        ListNode nextNode = node.next;
        node.val = nextNode.val;
        node.next = nextNode.next;
        nextNode.next = null;
    }
}

Explanation

1. copy value from the next node

2. connect the current node to next.next node

3. disconnect next node to next.next node

bad code

class Solution {
    public void deleteNode(ListNode node) {
        node.val = node.next.val;
        node.next = node.next.next;
    }
}

This is bad code. It may cause a memory leak.

The next node has to be disconnected.