程式語言 - LeetCode - C++ - 2095. Delete the Middle Node of a Linked List

題目：


解答：

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode() : val(0), next(nullptr) {}
 *     ListNode(int x) : val(x), next(nullptr) {}
 *     ListNode(int x, ListNode *next) : val(x), next(next) {}
 * };
 */
class Solution {
public:
    ListNode* deleteMiddle(ListNode* head) {
        int cnt = 0;
        ListNode *p0 = head;
        ListNode *p1 = head;

        while (p0) {
            cnt += 1;
            p0 = p0->next;
        }
        cnt >>= 1;

        if (cnt <= 0) {
            return NULL;
        }

        p0 = head;
        p1 = head;
        while (cnt--) {
            p0 = p1;
            p1 = p1->next;
        }
        p0->next = p1->next;

        return head;
    }
};