题解 | #两个链表的第一个公共结点#

/*
public class ListNode
{
    public int val;
    public ListNode next;
    public ListNode (int x)
    {
        val = x;
    }
}*/
class Solution {
    public ListNode FindFirstCommonNode(ListNode pHead1, ListNode pHead2) {
        ListNode pa = pHead1;
        ListNode pb = pHead2;
        if (pa == null || pb == null) return null;
        int times = 0;
        while (true) {
            if (pa == pb) return pa;
            pa = pa.next;
            pb = pb.next;
            if (pa == null) {
                if (times == 2) return null;
                pa = pHead2;
                times++;
            }
            if (pb == null) {
                if (times == 2) return null;
                pb = pHead1;
                times++;
            }
        }
    }
}