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) {
        ListNode *p1,*p2;
		p1=pHead1;
		p2=pHead2;
		int len1=0,len2=0;
		while(p1!=nullptr)
		{
			len1++;
			p1=p1->next;
		}
		while(p2!=nullptr)
		{
			len2++;
			p2=p2->next;
		}
		int n=len1>len2?(len1-len2):(len2-len1);
		p1=pHead1;
		p2=pHead2;
		for(int i=n;i>0;i--)
		{
			if(len1>len2)
			{
				p1=p1->next;
			}
			else 
			{
				p2=p2->next;
			}
		}
		while(p1!=p2)
		{
			p1=p1->next;
			p2=p2->next;
		}
		return p1;
    }
};