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) {
        bool flag = false;
        int len1 = 0, len2 = 0;
        ListNode* temp1 = pHead1;
        while(temp1!=NULL){
            temp1 = temp1->next;
            len1++; 
        }
        ListNode* temp2 = pHead2;
        while(temp2!=NULL){
            temp2 = temp2->next;
            len2++;
        }
        int dis = abs(len1 - len2);
        temp1 = pHead1, temp2 = pHead2;
        if(len1 < len2){
            while(dis > 0){temp2 = temp2->next;dis--;}
        }else if(len1 > len2){
            while(dis > 0){temp1 = temp1->next;dis--;}
        }
        while(temp1 != NULL)
        {
            if(temp1->val == temp2->val){
                flag = true;
                break;
            }
            temp1 = temp1->next;
            temp2 = temp2->next;
        }
        if(flag){
            return temp1;
        }else{
            return NULL;
        }
    }
};