/
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode next;
* ListNode(int x) : val(x), next(NULL) {}
* };
/
class Solution {
public:
ListNode findFirstCommonNode(ListNode headA, ListNode *headB) {
auto p = headA, q = headB;
while (p != q)
{
if(p) p = p->next;
else p = headB;
if(q) q = q->next;
else q = headA;
}
return p;
}
};