203. Remove Linked List Elements

First, the topic

1, examining

　　

2. Analysis

Removes a node with a value of Val in the linked list.

Second, the answer

1, Ideas:

Method One,

Create a header node, and delete the value in Val one by one.

     PublicListNode removeelements (ListNode head,intval) {             if(Head = =NULL)return NULL; ListNode Fakehead=NewListNode (0);  while(Head! =NULL&& Head.val = = val)//dealing with head nodes.Head =Head.next; Fakehead.next=Head;  while(Head! =NULL&& Head.next! =NULL) {            if(Head.next.val = =val) Head.next=Head.next.next; ElseHead=Head.next; }        returnFakehead.next; }

Optimization: Use pre, cur pointers to make the code more concise

     PublicListNode RemoveElements3 (ListNode head,intval) {        if(Head = =NULL)return NULL; ListNode Fakehead=NewListNode (0); Fakehead.next=Head; ListNode Curr= Head, prev =Fakehead;  while(Curr! =NULL) {            if(Curr.val = =val) Prev.next=Curr.next; Elseprev=Prev.next; Curr=Curr.next; }        returnFakehead.next; }

Method Two,

Using recursion

     Public int val) {                ifnull)             return NULL ;                 = removeelements (Head.next, Val);         return Head.val = = val? head.next:head;    }

203. Remove Linked List Elements