92. 反转链表 II

92. Reverse Linked List II

题目描述

反转从位置 m 到 n 的链表。请使用一趟扫描完成反转。

说明:

1 ≤ m ≤ n ≤ 链表长度。

LeetCode92. Reverse Linked List II中等

示例:

Java 实现

public class ListNode {

    int val;

    ListNode next;

    ListNode(int x) {

        val = x;

    }

    @Override

    public String toString() {

        return val + "->" + next;

    }

}

import java.util.Stack;

class Solution {

    public ListNode reverseBetween(ListNode head, int m, int n) {

        ListNode dummy = new ListNode(0);

        ListNode tail = dummy;

        Stack<Integer> stack = new Stack<>();

        int i = 1;

        while (head != null) {

            if (i < m) {

                tail.next = head;

                tail = tail.next;

            } else if (i >= m && i <= n) {

                stack.push(head.val);

            } else if (i > n) {

                break;

            }

            head = head.next;

            i++;

        }

        while (!stack.isEmpty()) {

            tail.next = new ListNode(stack.pop());

            tail = tail.next;

        }

        tail.next = head;

        return dummy.next;

    }

}

相似题目

• 206. 反转链表 Reverse Linked List

参考资料

• https://leetcode.com/problems/reverse-linked-list-ii/
• https://leetcode-cn.com/problems/reverse-linked-list-ii/