Added tests 11-31

Author: ThanhNIT

src/main/python/g0001_0100/s0015_3sum/Solution0015.py

@@ -3,6 +3,8 @@
 # #Top_Interview_150_Two_Pointers #Big_O_Time_O(n*log(n))_Space_O(n^2)
 # #2025_07_22_Time_581_ms_(56.92%)_Space_20.72_MB_(36.56%)
 
+from typing import List
+
 class Solution:
     def threeSum(self, nums: List[int]) -> List[List[int]]:
         nums.sort()

src/main/python/g0001_0100/s0015_3sum/Solution0015_test.py

@@ -0,0 +1,12 @@
+import unittest
+from Solution0015 import Solution
+
+class SolutionTest(unittest.TestCase):
+    def test_threeSum(self):
+        self.assertEqual(Solution().threeSum([-1, 0, 1, 2, -1, -4]), [[-1, -1, 2], [-1, 0, 1]])
+
+    def test_threeSum2(self):
+        self.assertEqual(Solution().threeSum([]), [])
+
+    def test_threeSum3(self):
+        self.assertEqual(Solution().threeSum([0]), [])

src/main/python/g0001_0100/s0017_letter_combinations_of_a_phone_number/Solution0017.py

@@ -3,6 +3,8 @@
 # #Udemy_Backtracking/Recursion #Top_Interview_150_Backtracking #Big_O_Time_O(4^n)_Space_O(n)
 # #2025_07_22_Time_0_ms_(100.00%)_Space_17.68_MB_(92.03%)
 
+from typing import List
+
 class Solution:
     def letterCombinations(self, digits: str) -> List[str]:
         if not digits:

src/main/python/g0001_0100/s0017_letter_combinations_of_a_phone_number/Solution0017_test.py

@@ -0,0 +1,33 @@
+import unittest
+from Solution0017 import Solution
+
+class SolutionTest(unittest.TestCase):
+    def test_letterCombinations(self):
+        self.assertEqual(
+            Solution().letterCombinations("23"),
+            ["ad", "ae", "af", "bd", "be", "bf", "cd", "ce", "cf"],
+        )
+
+    def test_letterCombinations2(self):
+        self.assertEqual(Solution().letterCombinations(""), [])
+
+    def test_letterCombinations3(self):
+        self.assertEqual(Solution().letterCombinations("2"), ["a", "b", "c"])
+
+    def test_letterCombinations4(self):
+        self.assertEqual(Solution().letterCombinations("4"), ["g", "h", "i"])
+
+    def test_letterCombinations5(self):
+        self.assertEqual(Solution().letterCombinations("5"), ["j", "k", "l"])
+
+    def test_letterCombinations6(self):
+        self.assertEqual(Solution().letterCombinations("6"), ["m", "n", "o"])
+
+    def test_letterCombinations7(self):
+        self.assertEqual(Solution().letterCombinations("7"), ["p", "q", "r", "s"])
+
+    def test_letterCombinations8(self):
+        self.assertEqual(Solution().letterCombinations("8"), ["t", "u", "v"])
+
+    def test_letterCombinations9(self):
+        self.assertEqual(Solution().letterCombinations("9"), ["w", "x", "y", "z"])

src/main/python/g0001_0100/s0019_remove_nth_node_from_end_of_list/Solution0019.py

@@ -2,6 +2,13 @@
 # #Algorithm_I_Day_5_Two_Pointers #Level_2_Day_3_Linked_List #Top_Interview_150_Linked_List
 # #Big_O_Time_O(L)_Space_O(L) #2025_07_22_Time_0_ms_(100.00%)_Space_17.70_MB_(84.76%)
 
+from typing import Optional
+
+class ListNode:
+    def __init__(self, val=0, next=None):
+        self.val = val
+        self.next = next
+
 # Definition for singly-linked list.
 # class ListNode:
 #     def __init__(self, val=0, next=None):

src/main/python/g0001_0100/s0019_remove_nth_node_from_end_of_list/Solution0019_test.py

@@ -0,0 +1,42 @@
+import unittest
+import importlib
+
+mod = importlib.import_module('Solution0019')
+
+class ListNode:
+    def __init__(self, val=0, next=None):
+        self.val = val
+        self.next = next
+
+    def __str__(self):
+        return ""
+
+def construct_linked_list(values):
+    dummy = ListNode(0)
+    curr = dummy
+    for v in values:
+        curr.next = ListNode(v)
+        curr = curr.next
+    return dummy.next
+
+
+def to_string(head):
+    parts = []
+    curr = head
+    while curr is not None:
+        parts.append(str(curr.val))
+        curr = curr.next
+    return ", ".join(parts)
+
+class SolutionTest(unittest.TestCase):
+    def test_removeNthFromEnd(self):
+        mod.ListNode = ListNode
+        node1 = construct_linked_list([1, 2, 3, 4, 5])
+        result = mod.Solution().removeNthFromEnd(node1, 2)
+        self.assertEqual(to_string(result), "1, 2, 3, 5")
+
+    def test_removeNthFromEnd2(self):
+        mod.ListNode = ListNode
+        node1 = ListNode(1)
+        result = mod.Solution().removeNthFromEnd(node1, 1)
+        self.assertIsNone(result)

src/main/python/g0001_0100/s0020_valid_parentheses/Solution0020_test.py

@@ -0,0 +1,18 @@
+import unittest
+from Solution0020 import Solution
+
+class SolutionTest(unittest.TestCase):
+    def test_isValid(self):
+        self.assertTrue(Solution().isValid("()"))
+
+    def test_isValid2(self):
+        self.assertTrue(Solution().isValid("()[]{}"))
+
+    def test_isValid3(self):
+        self.assertFalse(Solution().isValid("(]"))
+
+    def test_isValid4(self):
+        self.assertFalse(Solution().isValid("([)]"))
+
+    def test_isValid5(self):
+        self.assertTrue(Solution().isValid("{[]}"))

src/main/python/g0001_0100/s0021_merge_two_sorted_lists/Solution0021.py

@@ -3,6 +3,13 @@
 # #Level_1_Day_3_Linked_List #Udemy_Linked_List #Top_Interview_150_Linked_List
 # #Big_O_Time_O(m+n)_Space_O(m+n) #2025_07_22_Time_0_ms_(100.00%)_Space_17.70_MB_(61.28%)
 
+from typing import Optional
+
+class ListNode:
+    def __init__(self, val=0, next=None):
+        self.val = val
+        self.next = next
+
 # Definition for singly-linked list.
 # class ListNode:
 #     def __init__(self, val=0, next=None):

src/main/python/g0001_0100/s0021_merge_two_sorted_lists/Solution0021_test.py

@@ -0,0 +1,40 @@
+import unittest
+import importlib
+
+mod = importlib.import_module('Solution0021')
+
+class ListNode:
+    def __init__(self, val=0, next=None):
+        self.val = val
+        self.next = next
+
+
+def from_list(values):
+    dummy = ListNode(0)
+    curr = dummy
+    for v in values:
+        curr.next = ListNode(v)
+        curr = curr.next
+    return dummy.next
+
+
+def to_string(head):
+    parts = []
+    curr = head
+    while curr is not None:
+        parts.append(str(curr.val))
+        curr = curr.next
+    return ", ".join(parts)
+
+
+class SolutionTest(unittest.TestCase):
+    def test_mergeTwoLists(self):
+        mod.ListNode = ListNode
+        l1 = from_list([1, 2, 4])
+        l2 = from_list([1, 3, 4])
+        self.assertEqual(to_string(mod.Solution().mergeTwoLists(l1, l2)), "1, 1, 2, 3, 4, 4")
+
+
+    def test_mergeTwoLists2(self):
+        mod.ListNode = ListNode
+        self.assertEqual(to_string(mod.Solution().mergeTwoLists(ListNode(0), ListNode(0))), "0, 0") 

src/main/python/g0001_0100/s0022_generate_parentheses/Solution0022.py

@@ -3,6 +3,8 @@
 # #Top_Interview_150_Backtracking #Big_O_Time_O(2^n)_Space_O(n)
 # #2025_07_22_Time_0_ms_(100.00%)_Space_18.17_MB_(25.52%)
 
+from typing import List
+
 class Solution:
     def generateParenthesis(self, n: int) -> List[str]:
         ans = []