题解 | #删除链表的倒数第n个节点#

/**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 * };
 */

class Solution {
public:
    /**
     * 
     * @param head ListNode类 
     * @param n int整型 
     * @return ListNode类
     */
    ListNode* removeNthFromEnd(ListNode* head, int n) {
        // write code here

        if(head==nullptr)
        {
            return nullptr;
        }

        ListNode* fake = new ListNode(0); // 伪头节点
        fake->next = head;

        ListNode* fast = fake;
        ListNode* slow = fake;
        // 快慢指针
        for(int i=0; i<n; ++i)
        {
            fast = fast->next;
        }

        while(fast->next != nullptr)
        {
            fast = fast->next;
            slow = slow->next;
        }

        slow->next = slow->next->next; // 关键 

        return fake->next;

    }
};

快慢指针