83. Remove Duplicates from Sorte

Java

/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
public class Solution {
    public ListNode deleteDuplicates(ListNode head) {
        ListNode tmp=head;
        while(tmp!=null)
        {
            if(tmp.next!=null&&tmp.val==tmp.next.val)
            {
                tmp.next=tmp.next.next;
                
            }
            else
            {
                tmp=tmp.next;
            }
        }
        return head;
    }
}

Javascript

/**
 * Definition for singly-linked list.
 * function ListNode(val) {
 *     this.val = val;
 *     this.next = null;
 * }
 */
/**
 * @param {ListNode} head
 * @return {ListNode}
 */
var deleteDuplicates = function(head) {
        var tmp=head;
        while(tmp!==null)
        {
            if(tmp.next!==null&&tmp.val==tmp.next.val)
            {
                tmp.next=tmp.next.next;
                
            }
            else
            {
                tmp=tmp.next;
            }
        }
        return head;
};

优解

Java，用了递归的方法，想法很不错，比较难理解

public ListNode deleteDuplicates(ListNode head) {
        if(head == null || head.next == null)return head;
        head.next = deleteDuplicates(head.next);
        return head.val == head.next.val ? head.next : head;
}