RemoveKFromList

Given a singly linked list of integers l and an integer k, remove all elements from list l that have a value equal to k.

Example

• For l = [3, 1, 2, 3, 4, 5] and k = 3, the output should be solution(l, k) = [1, 2, 4, 5];

• For l = [1, 2, 3, 4, 5, 6, 7] and k = 10, the output should be solution(l, k) = [1, 2, 3, 4, 5, 6, 7].

Idea

Iteration + in-loop while loop

Iterate from the beginning and eliminate leading k

Iterate the mid-part and eliminate any single k or contiguous k

Code

ListNode<Integer> solution(ListNode<Integer> l, int k) {
    if(l==null){
        return l;
    }
    ListNode<Integer> head = null;
    while(l!=null){
        if(l.value!=k){
            head = l;
            break;
        }
        l = l.next;
    }
    
    ListNode<Integer> curr = head;
    while(curr!=null && curr.next!=null){
        if(curr.next.value==k){
            ListNode<Integer> kNode = curr.next;
            while(kNode!=null){
                if(kNode.value!=k){
                    break;
                }
                kNode = kNode.next;
            }
            curr.next = kNode;
        }
        curr = curr.next;
    }
    return head;
}