php实现删除链表中重复的节点

php实现删除链表中重复的节点

一、总结

二、php实现删除链表中重复的节点

题目描述：

在一个排序的链表中，存在重复的结点，请删除该链表中重复的结点，重复的结点不保留，返回链表头指针。 例如，链表1->2->3->3->4->4->5 处理后为 1->2->5

三、总结

代码一：

 <?php
 /*class ListNode{
     var $val;
     var $next = NULL;
     function __construct($x){
         $this->val = $x;
     }
 }*/
 function deleteDuplication($pHead)
 {
     if($pHead==null){ //各种情况判断
         return null;
     }
     if($pHead!=null&&$pHead->next==null){
         return $pHead;
     }
     $cur = $pHead;
     if($pHead->next->val==$pHead->val){
         $cur = $pHead->next->next;
         while($cur!=null&&$cur->val==$pHead->val){
             $cur = $cur->next;
         }
         return deleteDuplication($cur);
     }else{
         $cur = $pHead->next;
         $pHead->next = deleteDuplication($cur);
         return $pHead;
     }
 }

代码二：没ac

 <?php
 /*class ListNode{
     var $val;
     var $next = NULL;
     function __construct($x){
         $this->val = $x;
     }
 }*/
 function deleteDuplication($pHead)
 {
     $head=new ListNode(-1);
     $ans=$head;
     $head->next=$pHead;
     while($head){
         if($head->next&&$head->next->next){
             $l1=$head->next;
             $l2=$l1->next;
             while($l1->val==$l2->val){
                 $head->next=$l2->next;
                 if($l2->next) $l2=$l2->next;
                 else break;
             }
             $head=$head->next;
         }
     }
     return $ans->next;
 }

代码三：

 public static ListNode deleteDuplication(ListNode pHead) {

         ListNode first = new ListNode(-1);//设置一个trick

         first.next = pHead;

         ListNode p = pHead;
         ListNode last = first;
         while (p != null && p.next != null) {
             if (p.val == p.next.val) {
                 int val = p.val;
                 while (p!= null&&p.val == val)
                     p = p.next;
                 last.next = p;
             } else {
                 last = p;
                 p = p.next;
             }
         }
         return first.next;
     }

代码四：

 递归
 class Solution {
 public:
     ListNode* deleteDuplication(ListNode* pHead)
     {
         if (pHead==NULL)
             return NULL;
         if (pHead!=NULL && pHead->next==NULL)
             return pHead;

         ListNode* current;

         if ( pHead->next->val==pHead->val){
             current=pHead->next->next;
             while (current != NULL && current->val==pHead->val)
                 current=current->next;
             return deleteDuplication(current);
         }

         else {
             current=pHead->next;
             pHead->next=deleteDuplication(current);
             return pHead;
         }
     }
 };