题解 | #两个链表的第一个公共结点#

/*
struct ListNode {
	int val;
	struct ListNode *next;
	ListNode(int x) :
			val(x), next(NULL) {
	}
};*/
class Solution {
public:
    ListNode* FindFirstCommonNode( ListNode* pHead1, ListNode* pHead2) {
        // 利用set
		set<ListNode *> s;
		while(pHead1)
		{
			if(s.empty() || s.count(pHead1)==0)
			{
				s.emplace(pHead1);
			}
			pHead1 = pHead1->next;
		}

		while(pHead2)
		{
			if(s.count(pHead2))
				return pHead2;
			pHead2 = pHead2->next;
		}

		return nullptr;
    }
};