题目

代码

pub fn add_two_numbers(l1: Option<Box<ListNode>>, l2: Option<Box<ListNode>>) -> Option<Box<ListNode>> {
    let mut result = None;
    let mut temp = &mut result;
    let mut t = (l1,l2,0,0);
    loop{
        t = match t {
            (None,None,_,0) => break,
            (None,None,_,carry) => (None,None,carry,0),
            (None,Some(list),_,carry) | (Some(list),None,_,carry) if list.val + carry >= 10 => {
                (list.next,None,list.val+carry - 10,1)
            },
            (None,Some(list),_,carry) | (Some(list),None,_,carry) => {
                (list.next,None,list.val+carry,0)
            },
            (Some(l1),Some(l2),_,carry) if l1.val+l2.val+carry >= 10 => {
                (l1.next,l2.next,l1.val+l2.val+carry-10,1)
            },
            (Some(l1),Some(l2),_,carry) => {
                (l1.next,l2.next,l1.val+l2.val+carry,0)
            },
        };
        *temp = Some(Box::new(ListNode::new(t.2)));
        temp = &mut temp.as_mut().unwrap().next;
    }
    result
}