L19. Remove Nth Node From End of List

LinkedList

Given a linked list, remove the n-th node from the end of list and return its head.

Example:

Given linked list: 1->2->3->4->5, and n = 2.

After removing the second node from the end, the linked list becomes 1->2->3->5.

Note:

Given n will always be valid.

Follow up:

Could you do this in one pass?

Solution:

• n will be the gap from slow to fast

• when fast reach at end, we could delete slow.next.val;

public ListNode removeNode(ListNode head, int n){
    ListNode slow = head, fast = head;
    int count = 0;
    while(count < n && fast != null){
        fast = fast.next;
        count++;
    }
    
    if(fast == null) return head.next;
    while(fast.next != null){
        slow = slow.next;
        fast = fast.next;
    }
    slow.next = slow.next.next;
    return head;
    
}