數據結構和算法之單鏈表反轉

/**
 * 單鏈表反轉
 * Author : BlueSky 2019.10.29
 * Function：把每個節點的指針域由原來的指向下一個節點變爲指向其前一個節點
 * Example:
 *  輸入: 1->2->3->4->5->NULL
 *  輸出: 5->4->3->2->1->NULL
 */
public class LinkTableReversed {

    public static void main(String[] args) {
        Node node1 = new Node();
        Node node2 = new Node();
        Node node3 = new Node();
        Node node4 = new Node();
        Node node5 = new Node();

        node1.setNext(node2);
        node1.setData(1);

        node2.setNext(node3);
        node2.setData(2);

        node3.setNext(node4);
        node3.setData(3);

        node4.setNext(node5);
        node4.setData(4);

        node5.setNext(null);
        node5.setData(5);

        Node reversed = reversed(node1);
        System.out.println("node:" + reversed.getData());
        System.out.println("node next:" + reversed.getNext().getData());
        System.out.println("node next next:" + reversed.getNext().getNext().getData());

    }

    public static Node reversed(Node head) {
        // 頭爲空返回空
        if(head == null || head.getNext() == null){
            return null;
        }

        // 頭一個指針爲空
        Node preNode = null;
        // 當前指針爲head
        Node curNode = head;
        // 先設置爲null
        Node nextNode = null;

        while (true){
            if(curNode == null){
                break;
            }

            // 指定下一個node
            nextNode = curNode.getNext();
            // 當前指針指向前一個指針
            curNode.setNext(preNode);
            // 前一個指針和當前指針向後移動
            preNode = curNode;
            curNode = nextNode;
        }
        return preNode;
    }

    public static class Node {
        private Object data;

        private Node next;

        public Object getData() {
            return data;
        }

        public void setData(Object data) {
            this.data = data;
        }

        public Node getNext() {
            return next;
        }

        public void setNext(Node next) {
            this.next = next;
        }
    }
}