题解 | #反转链表#

需要习惯，rust中很多东西都被Option包裹

/**
 *  #[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 head ListNode类
        * @return ListNode类
    */
         pub fn ReverseList(&self, head: Option<Box<ListNode>>) -> Option<Box<ListNode>> {
         // write code here
         let mut pre = None;
         let mut head = head;
         while head.is_some(){
            //提前unwarp
            let mut cur = head.unwrap();
            head = cur.next;
            cur.next = pre;
            pre = Some(cur);
         }
         pre
     }
}