203_Remove_Linked_list_Elements

Leetcode 203: Remove Linked List Elements
Detailed video explanation: https://youtu.be/YIng7Pf6oa4
==============================================

C++:
====
Iterative:
----------
ListNode* removeElements(ListNode* head, int val) {
        if(!head) return head;
        ListNode *prev = nullptr, *curr = head;
        while(curr){
            if(curr->val == val){
                if(!prev)
                    head = curr->next;
                else
                    prev->next = curr->next;
            }else
                prev = curr;
            curr = curr->next;
        }
        return head;
    }
    
Recursive:
---------
ListNode* removeElements(ListNode* head, int val) {
        if(!head) return head;
        ListNode * h = removeElements(head->next, val);
        if(head->val == val) return h;
        head->next = h;
        return head;
    }
    
    
Java:
====
public ListNode removeElements(ListNode head, int val) {
        if(head == null) return head;
        ListNode prev = null, curr = head;
        while(curr != null){
            if(curr.val == val){
                if(prev == null)
                    head = curr.next;
                else
                    prev.next = curr.next;
            }else
                prev = curr;
            curr = curr.next;
        }
        return head;
    }
    
    
Python3:
=======
def removeElements(self, head: ListNode, val: int) -> ListNode:
    if head == None: return head
    prev, curr = None, head
    while curr != None:
        if curr.val == val:
            if prev == None: head = curr.next
            else: prev.next = curr.next
        else:prev = curr
        curr = curr.next
    return head