题解 | #两个链表的第一个公共结点#

//set,唯一，count（）只能是0or1；mulitset 不唯一，二者应用红黑树
class Solution {
public:
	ListNode* FindFirstCommonNode(ListNode* pHead1, ListNode* pHead2) {
		ListNode* pTail1=pHead1;
		ListNode* pTail2=pHead2;
		multiset< ListNode*>Hash;
		while (pTail1)
		{
			Hash.insert(pTail1);
			pTail1 = pTail1->next;
		}
		while (pTail2)
		{
			Hash.insert(pTail2);
			while (Hash.count(pTail2)==2)
			{
				return pTail2;
			}
			pTail2 = pTail2->next;
		}
		return nullptr;
	}
};