Sword finger offer 18 Delete the node of the linked list

Title Description

Given the head pointer of one-way linked list and the value of a node to be deleted , Define a function to delete the node .

Return the head node of the deleted linked list .

Be careful ： This question is different from the original one

 Example  1:
 Input : head = [4,5,1,9], val = 5
 Output : [4,1,9]
 explain :  Given that the value of your list is  5  Second node of , So after calling your function , The list should be  4 -> 1 -> 9.

 Example  2:
 Input : head = [4,5,1,9], val = 1
 Output : [4,5,9]
 explain :  Given that the value of your list is  1  The third node of , So after calling your function , The list should be  4 -> 5 -> 9.

 explain ：
 Ensure that the values of nodes in the list are different from each other 
 If you use  C  or  C++  Language , You don't need to  free  or  delete  Deleted node 

Answer key ：

1. python

class Solution:
    def deleteNode(self, head: ListNode, val: int) -> ListNode:
        dummy = ListNode()
        dummy.next = head
        cur = dummy
        while cur.next:
            if cur.next. val == val:
                cur.next = cur.next.next
                return dummy. next
            cur = cur. next
        else:
            return -1

2. C++

class Solution {
    
public:
    ListNode* deleteNode(ListNode* head, int val) {
    
        if(head->val == val) return head->next;
        ListNode *pre = head, *cur = head->next;
        while(cur != NULL && cur->val != val) {
    
            pre = cur;
            cur = cur->next;
        }
        if(cur != NULL) pre->next = cur->next;
        return head;
    }
};