题解 | #删除链表的倒数第n个节点#

 #include <stdlib.h>
int countList(struct ListNode* head)
 {
    int cnt = 0;
    while(head)
    {
        head= head->next;
        cnt++;
    }
    return cnt;
 }
struct ListNode* removeNthFromEnd(struct ListNode* head, int n ) {
    // write code here
    struct ListNode* tmp = NULL;
    struct ListNode* tmp_pre = NULL;
    int cnt = countList(head);
    int index = cnt -n;
    tmp = tmp_pre = head;
    while (index--) {
        tmp_pre=tmp;
        tmp=tmp->next;
    }
    if(head==tmp)
    {
        head = tmp->next;
    }
    else {
        tmp_pre->next = tmp->next;
        free(tmp);
    }

    return head;
}