[LeetCode][JavaScript]Remove Duplicates from Sorted List II

Remove Duplicates from Sorted List II

Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list.

For example,
Given 1->2->3->3->4->4->5, return 1->2->5.
Given 1->1->1->2->3, return 2->3.

https://leetcode.com/problems/remove-duplicates-from-sorted-list-ii/

 

 

 

 

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从链表中移除出现一次以上的节点。

递归，每次就比较两个节点：当前的和下一个。

三种情况：

1.有一个不存在，返回当前节点；

2.值相同，循环直到找到下一个不同的节点，递归；

3.值不同，留下当前节点，后面的节点递归，拼接起来作为返回值。 

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