【LeetCode】237 & 203

237 - Delete Node in a Linked List

Write a function to delete a node (except the tail) in a singly linked list, given only access to that node.

Supposed the linked list is 1 -> 2 -> 3 -> 4 and you are given the third node with value 3, the linked list should become 1 -> 2 -> 4 after calling your function.

Hide Tags: Linked List

struct ListNode{
    int val;
    ListNode *next;
    ListNode(int x):val(x), next(NULL){}
};
void deleteNode(ListNode *node)
{
    /*the main problem is that we can not know the pre ListNode of node,
      so we have to copy the val one by one*/
    ListNode *cur=node, *post=cur->next;
    while(post)
    {
        cur->val=post->val;
        if(post->next==NULL)
            cur->next=NULL;
        else
            cur=post;
        post=cur->next;
    }
}

203 - Remove Linked List Elements

Remove all elements from a linked list of integers that have value val.

Example
Given: 1 --> 2 --> 6 --> 3 --> 4 --> 5 --> 6, val = 6
Return: 1 --> 2 --> 3 --> 4 --> 5

ListNode* removeElements(ListNode* head, int val)
{
    ListNode *newhead=new ListNode(-1);
    newhead->next=head;
    ListNode *pre=newhead;
    ListNode *cur=head;
    while(cur)
    {
        if(cur->val!=val)
            pre=pre->next;
        else
            pre->next=cur->next;
        cur=cur->next;
    }
}