题解 | #删除有序链表中重复的元素-II#

<?php

/*class ListNode{
    var $val;
    var $next = NULL;
    function __construct($x){
        $this->val = $x;
    }
}*/

/**
 * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
 *
 * 
 * @param head ListNode类 
 * @return ListNode类
 */
function deleteDuplicates( $head )
{
    // write code here
    $dict = [];
    $cur = $head;
    while($cur){
        $dict[$cur->val] += 1;
        $cur = $cur->next;
    }
    $res = new ListNode(0);
    $res->next = $head;
    $cur = $res;
    while($cur->next){
        if($dict[$cur->next->val] != 1){
            $cur->next = $cur->next->next;
        }else{
            $cur = $cur->next;
        }
        
    }
    return $res->next;
}