考研那段时间记得太牢了。
当然也是简单题。。

/*** Definition for singly-linked list.* public class ListNode {*     int val;*     ListNode next;*     ListNode(int x) {*         val = x;*         next = null;*     }* }*/
public class Solution {public ListNode getIntersectionNode(ListNode headA, ListNode headB) {int lengthA = getLength(headA), lengthB = getLength(headB);int step = Math.abs(lengthA-lengthB);if(lengthA > lengthB){headA = forward(headA, step);}else{headB = forward(headB, step);}while(headA!=null && headB != null){if(headA == headB)return headA;headA = headA.next;headB = headB.next;}return null;}public int getLength(ListNode head){int length = 0;ListNode p = head;while(p!=null){p = p.next;length ++;}return length;}public ListNode forward(ListNode head, int step){while(step>0){head = head.next;step --;}return head;}
}