Remove Nth Node From End of List
Given a linked list, remove the nth node from the end of list and return its head.
Example
Given linked list: 1->2->3->4->5->null, and n = 2.
After removing the second node from the end, the linked list becomes 1->2->3->5->null.
Note
The minimum number of nodes in list is n.
Challenge
O(n) time
Solution: One Pass using Fast Slow Pointers
O(n) time, O(1) space
ListNode removeNthFromEnd(ListNode head, int n) {
if (head == null) {
return null;
}
ListNode slow = head;
ListNode fast = slow;
for (int i = 0; i < n; i++) {
if (fast.next == null) {
return head.next;
}
fast = fast.next;
}
while (fast.next != null) {
fast = fast.next;
slow = slow.next;
}
slow.next = slow.next.next;
return head;
}
