题解 | #链表中倒数最后k个结点#

/**
 *  #[derive(PartialEq, Eq, Debug, Clone)]
 *  pub struct ListNode {
 *      pub val: i32,
 *      pub next: Option<Box<ListNode>>
 *  }
 * 
 *  impl ListNode {
 *      #[inline]
 *      fn new(val: i32) -> Self {
 *          ListNode {
 *              val: val,
 *              next: None,
 *          }
 *      }
 *  }
 */
struct Solution{

}

impl Solution {
    fn new() -> Self {
        Solution{}
    }

    /**
    * 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 pHead ListNode类 
        * @param k int整型 
        * @return ListNode类
    */
   pub fn FindKthToTail(&self, pHead: Option<Box<ListNode>>, k: i32) -> Option<Box<ListNode>> {
        // write code here
        let mut fast = pHead.clone();
        for i in 0..k {
            if fast.is_none() {
                return None;
            }
            fast = fast.unwrap().next;
        }
        let mut slow = pHead;
        while fast.is_some() {
            fast = fast.unwrap().next;
            slow = slow.unwrap().next;
        }
        return slow;
    }
}