Remove Duplicates from Sorted List
<p>Given the <code>head</code> of a sorted linked list, <em>delete all duplicates such that each element appears only once</em>. Return <em>the linked list <strong>sorted</strong> as well</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/solution/0000-0099/0083.Remove%20Duplicates%20from%20Sorted%20List/images/list1.jpg" style="width: 302px; height: 242px;" />
<pre>
<strong>Input:</strong> head = [1,1,2]
<strong>Output:</strong> [1,2]
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/solution/0000-0099/0083.Remove%20Duplicates%20from%20Sorted%20List/images/list2.jpg" style="width: 542px; height: 222px;" />
<pre>
<strong>Input:</strong> head = [1,1,2,3,3]
<strong>Output:</strong> [1,2,3]
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li>The number of nodes in the list is in the range <code>[0, 300]</code>.</li>
	<li><code>-100 &lt;= Node.val &lt;= 100</code></li>
	<li>The list is guaranteed to be <strong>sorted</strong> in ascending order.</li>
</ul>
Linked List
// Definition for singly-linked list.
// #[derive(PartialEq, Eq, Clone, Debug)]
// pub struct ListNode {
//   pub val: i32,
//   pub next: Option<Box<ListNode>>
// }
//
// impl ListNode {
//   #[inline]
//   fn new(val: i32) -> Self {
//     ListNode {
//       next: None,
//       val
//     }
//   }
// }
impl Solution {
    pub fn delete_duplicates(head: Option<Box<ListNode>>) -> Option<Box<ListNode>> {
        let mut dummy = Some(Box::new(ListNode::new(i32::MAX)));
        let mut p = &mut dummy;

        let mut current = head;
        while let Some(mut node) = current {
            current = node.next.take();
            if p.as_mut().unwrap().val != node.val {
                p.as_mut().unwrap().next = Some(node);
                p = &mut p.as_mut().unwrap().next;
            }
        }
        dummy.unwrap().next
    }
}
