public ListNode getIntersectionNode(ListNode headA, ListNode headB) {
ListNode p1=headA;
ListNode p2=headB;
while(p1!=p2){
if(p1==null){
p1=headB;
}else{
p1=p1.next;
}
if(p2==null){
p2=headA;
}
else{
p2=p2.next;
}
}
return p1;
}