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
        int count = 0;
        ListNode *p = head;
        ListNode *q;
        while(p!= NULL){
            count++;
            p = p->next;
        }
        
        if(count == n){
            p = head->next;
            head->next = NULL;
            return p; 
        }
        
        count = count-n;
        p = head;
        
        while(count > 0){
            q = p;
            p = p->next;
            if(count == 1){
                if(p != NULL){
                    q->next = p->next;
                    p = NULL;
                }else{
                    q->next = NULL;
                }
            }
            count--;
        }
        return head;
    }
};