021_merge-two-sorted-lists.py

# Definition for singly-linked list.
class ListNode(object):
    def __init__(self, x):
        self.val = x
        self.next = None


class Solution(object):
    def mergeTwoLists(self, l1, l2):
        """
        :type l1: ListNode
        :type l2: ListNode
        :rtype: ListNode
        """
        l3 = current = ListNode(0)
        while l1 and l2:
            if l1.val < l2.val:
                current.next = ListNode(l1.val)
                current = current.next
                l1 = l1.next
            else:
                current.next = ListNode(l2.val)
                current = current.next
                l2 = l2.next

        if l1:
            current.next = l1
        elif l2:
            current.next = l2

        return l3.next


def CreateList(num_list):
    head = n = ListNode(0)
    for l in num_list:
        n.next = ListNode(l)
        n = n.next
    return head.next

def PrintList(current):
    numbers = []
    while current:
        numbers.append(current.val)
        current = current.next
    return numbers

l1 = CreateList([2, 3, 4])
l2 = CreateList([1, 5, 6])

l3 = Solution().mergeTwoLists(l1, l2)
print(PrintList(l3))