提示:
使用快慢指针。
代码:
/** * Definition for singly-linked list. * struct ListNode { * int val; * ListNode *next; * ListNode(int x) : val(x), next(NULL) {} * }; */ class Solution { public: ListNode* middleNode(ListNode* head) { ListNode *fast = head; ListNode *slow = head; while(fast && fast->next) { fast = fast->next->next; slow = slow->next; } return slow; } };