剑指Offer 37题 两个链表的第一个公共节点 Java版

package test;public class GetFirstCommonNode {class ListNode{public String key;public ListNode next;}public ListNode findFirstCommonNode(ListNode headOne, ListNode headTwo){if(headOne == null || headTwo == null){return null;}int length1 = getListLength(headOne); int length2 = getListLength(headTwo);int lenghtdif = length1 - length2;ListNode headLong = headOne;ListNode headShort = headTwo;if(length2 > length1){headLong = headTwo;headShort = headOne;lenghtdif = length2 - length1;}for(int i=0; i<lenghtdif; ++i){headLong = headLong.next;}while((headLong!=null)&&(headShort!=null)&&(headLong!=headShort)){headLong = headLong.next;headShort = headShort.next;}ListNode firstCommonNode = headLong;return firstCommonNode;}public int getListLength(ListNode head){int length = 0;ListNode node = head;while(node!=null){++length;node = node.next;}return length;}public static void main(String[] args) {// TODO Auto-generated method stubGetFirstCommonNode node = new GetFirstCommonNode();ListNode a = node.new ListNode();a.key = "a";ListNode b = node.new ListNode();b.key = "b";ListNode e = node.new ListNode();e.key = "e";ListNode d = node.new ListNode();d.key = "d";ListNode f = node.new ListNode();f.key = "f";ListNode h = node.new ListNode();h.key = "h";f.next = d;d.next = b;b.next = a;h.next = e;e.next = b;b.next = a;ListNode node1 = node.findFirstCommonNode(f, h);System.out.println(node1.key);}}

另外书上还提到，还有蛮力法和用两个栈的方法，没事的时候可以练练手。