Java 代码

class Solution 
{
    public ListNode findFirstCommonNode(ListNode headA, ListNode headB) 
    {
        ListNode a = headA;
        ListNode b = headB;

        while ( a != b)
        {
            if (a == null)
                a = headB;
            else 
                a = a.next;

            if (b == null)
                b = headA;
            else
                b = b.next;
        }
        return a;
    }
}