单链表和双向链表反转 java

最新推荐文章于 2024-07-22 15:15:11 发布

转载最新推荐文章于 2024-07-22 15:15:11 发布 · 2.2k 阅读

文章标签：

#单链表 #双链表 #反转 #java

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本文介绍了一种高效的链表反转算法，包括单向链表和双向链表的反转，并提供了具体的Java实现代码。该算法的时间复杂度为O(N)，额外空间复杂度为O(1)。

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题目要求：
反转单向和双向链表
【题目】分别实现反转单向链表和反转双向链表的函数。
【要求】如果链表长度为N，时间复杂度要求为O(N)，额外空间
复杂度要求为O(1)

public class e7_reverseLink {

    public static class Node {
        public int value;
        public Node next;

        public Node(int data) {
            this.value = data;
        }
    }

    public static Node reverseList(Node head) {
        Node pre = null;
        Node next = null;
        while (head != null) {
            next = head.next;
            head.next = pre;
            pre = head;
            head = next;
        }
        return pre;
    }

    public static class DoubleNode {
        public int value;
        public DoubleNode last;
        public DoubleNode next;

        public DoubleNode(int data) {
            this.value = data;
        }
    }

    public static DoubleNode reverseList(DoubleNode head) {
        DoubleNode pre = null;
        DoubleNode next = null;
        while (head != null) {
            next = head.next;
            head.next = pre;
            head.last = next;
            pre = head;
            head = next;
        }
        return pre;
    }

    public static void printLinkedList(Node head) {
        System.out.print("Linked List: ");
        while (head != null) {
            System.out.print(head.value + " ");
            head = head.next;
        }
        System.out.println();
    }

    public static void printDoubleLinkedList(DoubleNode head) {
        System.out.print("Double Linked List: ");
        DoubleNode end = null;
        while (head != null) {
            System.out.print(head.value + " ");
            end = head;