（整理）Java实现链表--找到两个链表的第一个公共结点（网易笔试题2016）

import java.util.*;class Node{Node next = null;int data;public Node(int data){this.data = data;}}public class MyLinkedList {Node head = null;public void addNode(int d){Node newNode = new Node(d);if(head == null){head = newNode;return;}Node tmp = head;while(tmp.next != null){tmp = tmp.next;}tmp.next = newNode;}public Boolean deleteNode(int index){if(index<1||index>length()){return false;}if(index == 1){head = head.next;return true;}int i = 2;Node preNode = head;Node curNode = preNode.next;while(curNode != null){if(i == index){preNode.next = curNode.next;return true;}preNode = curNode;curNode = curNode.next;i++;}return true;}public int length(){int length = 0;Node tmp = head;while(tmp != null){length++;tmp = tmp.next;}return length;}public void printList(){Node tmp = head;while(tmp != null){System.out.println(tmp.data);tmp = tmp.next;}}public static Node findNode(MyLinkedList list,int index){int i;Node p = list.head;for(i = 1; i<index; i++){p = p.next;}return p;}public static Node getFirstMeetNode(Node h1,Node h2){//关键的函数Node p1 = h1;Node p2 = h2;    while(p1.next != null && p2.next != null){//作两个链表的长度差    p1 = p1.next;    p2 = p2.next;    }    Node p3,p4,p;    if(p1.next == null){    p3 = p2;    p4 = h2;    p = h1;    }    else{    p3 = p1;    p4 = h1;    p = h2;    }while(p3.next != null){//长链表到|list1.length()-list2.length()|的位置 此位置与短链表head到第一个公共结点的距离相等    p3 = p3.next;    p4 = p4.next;    }while(p != p4 && p != null){//通过比较是否相等，找到公共结点p = p.next;p4 = p4.next;}return p;//返回第一个公共结点    }public static void main(String[] args){MyLinkedList list = new MyLinkedList();MyLinkedList list1 = new MyLinkedList();//创建两个列表MyLinkedList list2 = new MyLinkedList();list1.addNode(7);list1.addNode(6);list1.addNode(5);list1.addNode(4);list1.addNode(3);list1.addNode(2);list1.addNode(1);list2.addNode(5);list2.addNode(4);Node p1 = findNode(list1,5);Node p2 = findNode(list2,2);p2.next = p1;//连接两个链表System.out.println("list1");list1.printList();System.out.println("list2");list2.printList();Node p = getFirstMeetNode(list1.head,list2.head);System.out.println("FMN="+p.data);while(true){Scanner s = new Scanner(System.in);String cz = s.next();if(cz.equals("add")){int data = s.nextInt();list.addNode(data);list.printList();}else if(cz.equals("del")){int index = s.nextInt();list.deleteNode(index);list.printList();}else if(cz.equals("len")){System.out.println("Len= "+list.length());}}}}