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
 */
struct ListNode* removeNthFromEnd(struct ListNode* head, int n ) {
    // write code here
    int cnt = 0;
    struct ListNode *curr = head;
    struct ListNode *next = NULL;
    struct ListNode *prev = NULL;

    while(curr) {
        curr = curr->next;
        cnt++;
    }
    if (cnt < n)
        return head;
    curr = head;
    while(curr) {
        next = curr->next;
        if (cnt == n) {
            if(prev)
                prev->next = next;
            else
                head = next;
        }
        prev = curr;
        curr = curr->next;
        cnt--;
    }
    return head;
}