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;
        }    
    }
};