Leetcode---206. 反转链表

最新推荐文章于 2025-03-02 12:31:27 发布

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本文详细介绍了如何实现单向链表和双向链表的反转操作，通过具体代码示例，展示了链表节点的定义、初始化、遍历以及反转过程，是理解链表数据结构及其操作的良好参考资料。

单向链表的反转：

public class ReverseList {
	public static void main(String[] args) {
		Node head1 = new Node(1);
		head1.next = new Node(2);
		head1.next.next = new Node(3);
		printLinkedList(head1);
		head1 = reverseList(head1);
		printLinkedList(head1);
		
	}

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

		public Node(int data) {
			this.value = data;
		}
	}
	
	private static void printLinkedList(Node head) {
		System.out.println("单向链表为：");
		while(head!=null){
			System.out.print(head.value+" ");
			head = head.next;
		}
		System.out.println();
	}
	
	private 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;
	}
}

双向链表的反转

public class ReverseList {
	
	public static class DoubleNode {
		public int value;
		public DoubleNode last;
		public DoubleNode next;
		
		public DoubleNode(int data){
			this.value = data;
		}
	}
	
	public static void main(String[] args) {
		DoubleNode head2 = new DoubleNode(1);
		head2.next = new DoubleNode(2);
		head2.next.last = head2;
		head2.next.next = new DoubleNode(3);
		head2.next.next.last = head2.next;
		head2.next.next.next = new DoubleNode(4);
		head2.next.next.next.last = head2.next.next;
		printDoubleLinkedList(head2);
		printDoubleLinkedList(reverseList(head2));
	}

	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;
	}

	private static void printDoubleLinkedList(DoubleNode head) {
		System.out.println("打印双向链表");
		DoubleNode end = null;
		while(head!=null){
			System.out.print(head.value+" ");
			end = head;
			head = head.next;
		}
		System.out.print("|");
		while(end!=null){
			System.out.print(end.value+" ");
			end = end.last;
		}
		System.out.println();
	}
}