LeetCode - Algorithms - 19. Remove Nth Node From End of List

Java

Hint: Maintain two pointers and update one with a delay of n steps.

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/**
 * Definition for singly-linked list.
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) { val = x; }
 * }
 */
class Solution {
    public ListNode removeNthFromEnd(ListNode head, int n) {
    	ListNode fast = head, slow = head;
    	for(int i=0;i<n;i++)
    		fast = fast.next;
    	if (fast==null)
    		head = head.next;
    	else {
    		while(fast.next!=null) {
    			fast = fast.next;
    			slow = slow.next;
    		}
    		ListNode p = slow.next;
    		slow.next = p.next;
    		p.next = null;
    	}
        return head;       
    }
}

Submission Detail

  • 208 / 208 test cases passed.
  • Runtime: 6 ms, faster than 98.72% of Java online submissions for Remove Nth Node From End of List.
  • Memory Usage: 38 MB, less than 100.00% of Java online submissions for Remove Nth Node From End of List.

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