[21] Merge Two Sorted Lists

https://leetcode.com/problems/merge-two-sorted-lists/description/

• algorithms
• Easy (44.15%)
• Source Code: 21.merge-two-sorted-lists.py
• Total Accepted: 553.4K
• Total Submissions: 1.2M
• Testcase Example: '[1,2,4]\n[1,3,4]'

Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.

Example:

Input: 1->2->4, 1->3->4 Output: 1->1->2->3->4->4

# 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
        """
        l1_values, l2_values = [], []
        while l1:
            l1_values.append(l1.val)
            l1 = l1.next

        while l2:
            l2_values.append(l2.val)
            l2 = l2.next

        l1_values.extend(l2_values)
        l1_values.sort()

        len1 = len(l1_values)
        record, head = None, None
        for i in l1_values[::-1]:
            head = ListNode(i)
            head.next = record
            record = head

        return head