struct ListNode* deleteNode(struct ListNode* head, int val ) {
    if(head==NULL){
        return NULL;
    }
    
    struct ListNode* pre=NULL;
    struct ListNode* node=head;
    struct ListNode* next=head->next;

    while(node){
        int cur_val=node->val;
        if(cur_val==val){
            if(pre!=NULL){
                pre->next=next;
            }else{
                head=next;
            }
            break;
        }else{
            pre=node;
            node=next;
            if(next){
                next=next->next;
            }
        }
    }
    return head;
}