Leetcode #2. Add two numbers

There are two ways to do this. First is utilizing separate insert and append function (not leetcode-bound solution).

class node:
    def __init__(self,data,next=None):
        self.data=data
        self.next=next

class linked_list:
    def __init__(self):
        self.head=None

    def insert(self,data):
        new_node=node(data)
        new_node.next=self.head
        self.head=new_node

    def appending(self,data):
        cur = self.head
        while cur.next:
            cur = cur.next
        cur.next=node(data)

    def printing(self):
        cur=self.head
        while cur.next:
            print(cur.data)
            cur = cur.next
        print(cur.data)

LL=linked_list()
LL.insert(9)
LL.appending(9)


LL2=linked_list()
LL2.insert(5)
LL2.appending(2)


def adding(LL1,LL2):
    head_1=LL1.head
    head_2=LL2.head

    list1=[]
    list2=[]

    while head_1.next:
        list1.append(head_1.data)
        head_1=head_1.next
    list1.append(head_1.data)

    while head_2.next:
        list2.append(head_2.data)
        head_2 = head_2.next
    list2.append(head_2.data)

    int1=int(','.join([str(x) for x in list1[::-1]]).replace(',',''))
    int2 =int(','.join([str(x) for x in list2[::-1]]).replace(',',''))

    num_list=[int(d) for d in str(int1+int2)][::-1]

    LL3=linked_list()

    for x in range(len(num_list)):
        if x==0:
            LL3.insert(num_list[x])
        else:
            LL3.appending(num_list[x])

    LL3.printing()

adding(LL,LL2)

  

Another way is to follow Leetcode restrictions where we don't neccessarily have append and insert functions for LinkedList.

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def addTwoNumbers(self, l1: ListNode, l2: ListNode) -> ListNode:
        
        list1=[]
        list2=[]

        while l1.next:
            list1.append(l1.val)
            l1=l1.next
        list1.append(l1.val)

        while l2.next:
            list2.append(l2.val)
            l2 = l2.next
        list2.append(l2.val)

        int1=int(','.join([str(x) for x in list1[::-1]]).replace(',',''))
        int2 =int(','.join([str(x) for x in list2[::-1]]).replace(',',''))

        num_list=[int(d) for d in str(int1+int2)][::-1]
        
        cur=ListNode(1)
        
        l3=ListNode(num_list[0])
        l3.next=cur
        cur=l3
        
        for x in range(len(num_list)):
            while cur.next:
                cur=cur.next
            cur.next=ListNode(num_list[x])
                
        return l3.next.next