83. 删除排序链表中的重复元素 leetcode

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/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     public var val: Int
 *     public var next: ListNode?
 *     public init(_ val: Int) {
 *         self.val = val
 *         self.next = nil
 *     }
 * }
 */
class Solution {
    func deleteDuplicates(_ head: ListNode?) -> ListNode? {
         if head.self == nil{
            return head
        }else{
            var listN = head
            while listN?.next != nil{
                if listN?.val == listN?.next?.val{
                    listN?.next = listN?.next?.next
                }else{
                    listN = listN?.next
                }
                
            }
        }
        return head
    }
}