题解 | #删除链表的倒数第n个节点#

/**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 * };
 */
/**
 * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
 *
 * 
 * @param head ListNode类 
 * @param n int整型 
 * @return ListNode类
 */
#include <stdio.h>
#include <stdlib.h>
struct ListNode* removeNthFromEnd(struct ListNode* head, int n ) {
    struct ListNode *phead=(struct ListNode*)malloc(sizeof(struct ListNode));
    phead->next = head;
    // write code here
    if (head == NULL) {
        return NULL;
    }
    if (head->next == NULL) {
        free(head);
        head=NULL;
        return  head;
    }
    struct ListNode *p=phead;
    struct ListNode *pre=phead;
    struct ListNode *t;
    n=n+1;
    while (n--) {
        p=p->next;
    
    }
   
    while (p!=NULL) {
        pre = pre->next;
        p=p->next;
    }

    t=pre->next;
    pre->next =t->next;
    free(t);
   return phead->next;
}