hongtaoh

class Solution:
    # credit: https://www.youtube.com/watch?v=q1RR8gk47Cg
    def addStrings(self, num1: str, num2: str) -> str:
        i = len(num1) - 1
        j = len(num2) - 1
        carry = 0
        res = []
        while i >= 0 or j >= 0:
            int1 = int(num1[i]) if i >=0 else 0 
            int2 = int(num2[j]) if j >= 0 else 0

hongtaoh

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def mergeTwoLists(self, list1: Optional[ListNode], list2: Optional[ListNode]) -> Optional[ListNode]:
        dummy = ListNode()
        tail = dummy 
        while list1 and list2:

hongtaoh

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def mergeKLists(self, lists: List[Optional[ListNode]]) -> Optional[ListNode]:
        # credit: https://www.youtube.com/watch?v=q5a5OiGbT6Q
        if not lists or len(lists) == 0:
            return None 

hongtaoh

class Solution:
  """
  This is okay but unnecessarily complicated. 
  if a = [1, 2, 3], then a[4:] won't cause any errors. This will help me get a better solution.
  """
    def mergeAlternately(self, word1: str, word2: str) -> str:
        # len1 < len2
        len1, len2 = (len(word1), len(word2)) if len(word1) < len(word2) else (len(word2), len(word1))
        output = []

hongtaoh

class Solution:
    def moveZeroes(self, nums: List[int]) -> None:
        """
        Do not return anything, modify nums in-place instead.
        """
        l = 0
        for r in range(len(nums)):
            if nums[r] != 0:
                nums[l], nums[r]= nums[r], nums[l]
                l += 1