leetcode: 面试题 02.07. Intersection of Two Linked Lists LCCI

leetcode: 面试题 02.07. Intersection of Two Linked Lists LCCI

原题链接

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode *getIntersectionNode(ListNode *headA, ListNode *headB) {
        int len1 = getLinkedListLen(headA);
        int len2 = getLinkedListLen(headB);

        ListNode* cur = headA;
        ListNode* cur1 = headB;
        if (len1 > len2) {
            int n = len1 - len2;
            while (n--) {
                cur = cur->next;
            }

        } else {
            int n = len2 - len1;
            while (n--) {
                cur1 = cur1->next;
            }
        }
        
        while (cur != NULL) {
            if (cur == cur1) return cur;
            cur = cur->next;
            cur1 = cur1->next;
        }

        return NULL;
    }
private:
    int getLinkedListLen(ListNode* head) {
        int len = 0;
        ListNode* cur = head;
        while (cur != NULL) {
            cur = cur->next;
            len++;
        }
        return len;
    }
};