题解 | #链表中倒数最后k个结点#

一遍通过

• 判空
• 定义快慢指针
• fast指针先跑k个结点 - n=0,则从输出头指针，n+1， 结点后移1

struct ListNode* FindKthToTail(struct ListNode* pHead, int k ) {
    // write code here
    // 判空
    if(pHead == NULL)
    {
        return pHead;
    }
    
    int n = 0;
    struct ListNode * fast = pHead;
    struct ListNode * slow = pHead;
    while( fast != NULL && n < k)
    {
        fast = fast->next;
        n++;
    }
    
    if(fast == NULL && n == k)
    {
        return pHead;
    }
    
    if(fast == NULL && n < k)
    {
        return NULL;
    }
    
    
    while(fast != NULL)
    {
        slow = slow->next;
        fast = fast->next;
    }
    
    return slow;
}