题解 | #链表相加(二)#

# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None
#
# 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 head1 ListNode类 
# @param head2 ListNode类 
# @return ListNode类
#
class Solution:
    
    def addInList(self , head1: ListNode, head2: ListNode) -> ListNode:
        # write code here
        def reverseList(head):
            if head == None:
                return head
            current = head
            node = None
            while current:
                next_node = current.next
                current.next = node
                node = current
                current = next_node
            
            return node
        
        if head1 == None:
            return head2
        elif head2 == None:
            return head1
        
        head1_reverse = reverseList(head1)
        head2_reverse = reverseList(head2)
        dummpy = ListNode(0)
        node = dummpy
        carry = 0
        while (head1_reverse or head2_reverse or carry !=0 ):
            if head1_reverse:
                carry += head1_reverse.val
                head1_reverse = head1_reverse.next
            if head2_reverse:
                carry += head2_reverse.val
                head2_reverse = head2_reverse.next

            node.next = ListNode(carry % 10)
            node = node.next
            carry = carry // 10

        return reverseList(dummpy.next)