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) {
        int length1=0;
        int length2=0;
        auto p1 = pHead1;
        auto p2 = pHead2;
        while(p1!=NULL){
            length1++;
            p1=p1->next;
        }
        while(p2!=NULL){
            length2++;
            p2=p2->next;
        }
        int length = abs(length1 - length2);
        if(length1 > length2){
            for(int i=0;i<length;i++)pHead1=pHead1->next;
            while(pHead1!=pHead2){
                pHead1=pHead1->next;
                pHead2=pHead2->next;
            }
        }
        else{
            for(int i=0;i<length;i++)pHead2=pHead2->next;
            while(pHead1!=pHead2){
                pHead1=pHead1->next;
                pHead2=pHead2->next;
            }
        }
        return pHead1;
    }
};