合并两个有序链表

一 概述

将各自从小到大有序的两个链表head1 和head2 归并成一个从小到大有序链表。

二 Java代码实现

链表节点类(Node)

public class Node {

    int data;

    Node next;

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

    public int getData() {
        return data;
    }

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

    public Node getNext() {
        return next;
    }

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

合并有序链表类

public class MargeList {

    public static void main(String[] args) {

        Node head1 = new Node(1);
        Node n1 = new Node(3);
        Node n2 = new Node(5);
        head1.setNext(n1);
        n1.setNext(n2);

        Node head2 = new Node(2);
        Node n4 = new Node(4);
        Node n5 = new Node(6);
        head2.setNext(n4);
        n4.setNext(n5);

        Node result = marge(head1,head2);
        while (result!=null) {
            System.out.print(result.getData()+ "");
            result = result.getNext();
        }
    }

    private static  Node marge(Node head1,Node head2) {

        //判断空
        if(head1 == null || head2 == null) {
           return head1 == null? head2 : head1;
        }

        //判断合并后头节点
        Node node = head1.getData() <= head2.getData() ? head1:head2;

        //使用head1和head2的副本
        Node current1 = node == head1 ? head1:head2;
        Node current2 = node == head1 ? head2:head1;

        //使用临时空间
        Node temp1 = null;
        Node temp2 ;

        //判断哪个先比较完
        while(current1!=null&&current2!=null){

            if(current1.getData() <= current2.getData()){
                //当副本current1的值小于等于副本current2中的值，将小值放入临时空间temp1
                temp1 = current1;
                //继续比较current1中下一个值
                current1 = current1.getNext();
            }else {
                //使用临时空间temp2保存第一个元素小的副本current2的第二个节点及后续元素
                temp2 = current2.getNext();
                //将第一个值小的副本current2拷贝到临时空间temp1
                temp1.setNext(current2);
                //将较大值放入current2下一个节点
                current2.setNext(current1);
                //当副本current1的值不小于副本current2中的值，将小值放入临时空间temp1
                temp1 = current2;
                current2 = temp2;
            }
        }
        temp1.setNext(current1 == null ? current2 : current1);
        return node;
    }
}

三 合并结果

链表一：1 3 5

链表二：2 4 6

合并结果