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LeetCode-19题

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LeetCode-19题

给定一个链表的头节点，删除链表的倒数第n个节点，并返回删除后的头节点

class Solution {public ListNode removeNthFromEnd(ListNode head, int n) {// checkif (head == null || n <= 0) {return head;}// 双指针ListNode dummyHead = new ListNode(0, head);ListNode p1 = dummyHead;ListNode p2 = dummyHead;for (int i = 0; i < n; i++) {p2 = p2.next;}while (p2 != null && p2.next != null) {p2 = p2.next;p1 = p1.next;}// 此时删除的就是链表倒数第n个节点p1.next = p1.next.next;return dummyHead.next;}private static class ListNode {int val;ListNode next;public ListNode() {}public ListNode(int val) {this.val = val;}public ListNode(int val, ListNode next) {this.val = val;this.next = next;}}
}