Time Cost

14min49s

Implementation

Quick-Slow Pointers. When the quick pointer hits the boundary then stops.

Code

• Solution

  class Solution {
  public:
    ListNode* removeNthFromEnd(ListNode* head, int n) {
        ListNode dummy(0);
        dummy.next = head;
  
        ListNode* fast = &dummy;
        ListNode* slow = &dummy;
  
        for (int i = 0; i < n + 1; i++) fast = fast->next;
  
        while (fast) {
            fast = fast->next;
            slow = slow->next;
        }
  
        ListNode* toRemove = slow->next;
        slow->next = toRemove->next;
        return dummy.next;
    }
  };