51.Intersection of Two Linked Lists-相交链表

解析：双指针

public class Solution {
    public ListNode getIntersectionNode(ListNode headA, ListNode headB) {
        //双指针,到达终点后就交换
        ListNode p1 = headA;
        ListNode p2 =headB;
        while(p1!=p2) {
            p1=p1==null?headB:p1.next;
            p2=p2==null?headA:p2.next;
        }
        return p1;
    }
}