203.RemoveElements.cs

//203. Remove Linked List Elements
// Given the head of a linked list and an integer val, remove all the nodes of the linked list that has Node.val == val, and
// return the new head.
// definition for singly-linked list.
public class listnode
{
    public int val;
    public listnode next;
    public listnode(int val = 0, listnode next = null)
    {
        this.val = val;
        this.next = next;
    }
}

public class Solution
{
    public listnode RemoveElements(listnode head, int val)
    {
        listnode pivot = head;
        if (head == null)
        {
            return head;
        }
        while (head.val == val)
        {
            if (head.next == null)
                return null;
            head = head.next;
        }
        while (pivot != null)
        {
            while (pivot.next != null && pivot.next.val == val)
            {
                pivot.next = pivot.next.next;
            }
            pivot = pivot.next;
        }
        return head;
    }
}


public class Solution {
    public ListNode RemoveElements(ListNode head, int val) {
        if(head == null)
            return head;
        while(head.val == val){
            if(head.next == null)
                return null;
            head = head.next;
        }
        ListNode curr = head.next;
        ListNode prev = head;
        while(prev != null && curr !=null){
            if(curr.val == val)
                prev.next = curr.next;
            else
                prev = curr;
            curr = curr.next;
        }
        return head;
    }
}