adding algo

src/my_project/interviews/top_150_questions_round_22/ex_57_merge_two_sorted_linked_lists.py

@@ -0,0 +1,32 @@
+from typing import List, Union, Collection, Mapping, Optional
+from abc import ABC, abstractmethod
+
+# Definition for singly-linked list.
+class ListNode:
+    def __init__(self, x):
+        self.val = x
+        self.next = None
+
+class Solution:
+    def mergeTwoLists(self, l1: ListNode, l2: ListNode) -> ListNode:
+        # Create a dummy node to simplify edge cases
+        dummy = ListNode(0)
+        current = dummy
+
+        # Traverse both lists and merge
+        while l1 and l2:
+            if l1.val <= l2.val:
+                current.next = l1
+                l1 = l1.next
+            else:
+                current.next = l2
+                l2 = l2.next
+            current = current.next
+
+        # Attach remaining nodes from either list
+        if l1:
+            current.next = l1
+        if l2:
+            current.next = l2
+
+        return dummy.next

src/my_project/interviews_typescript/top_150_questions_round_1/ex_57_merge_two_sorted_linked_lists.ts

@@ -0,0 +1,29 @@
+import { ListNode } from './ListNode';        
+
+function mergeTwoLists(list1: ListNode | null, list2: ListNode | null): ListNode | null {
+    // Create a dummy node to simplify edge cases
+    const dummy = new ListNode(0);
+    let current = dummy;
+
+    // Traverse both lists and merge
+    while (list1 && list2) {
+        if (list1.val <= list2.val) {
+            current.next = list1;
+            list1 = list1.next;
+        } else {
+            current.next = list2;
+            list2 = list2.next;
+        }
+        current = current.next;
+    }
+
+    // Attach remaining nodes from either list
+    if (list1) {
+        current.next = list1;
+    }
+    if (list2) {
+        current.next = list2;
+    }
+
+    return dummy.next;
+}

tests/test_150_questions_round_22/test_57_merge_two_sorted_linked_lists_round_22.py

@@ -0,0 +1,73 @@
+import unittest
+from src.my_project.interviews.top_150_questions_round_22\
+.ex_57_merge_two_sorted_linked_lists import Solution, ListNode
+
+class MergeTwoLinkedListsTestCase(unittest.TestCase):
+
+    def create_linked_list(self, values):
+        """
+        Helper function to create a linked list from a list of values.
+        
+        :param values: List of node values
+        :return: Head of the linked list
+        """
+        if not values:
+            return None
+
+        head = ListNode(values[0])
+        current = head
+
+        for val in values[1:]:
+            current.next = ListNode(val)
+            current = current.next
+
+        return head
+
+    def linked_list_to_list(self, head):
+        """
+        Helper function to convert linked list to Python list.
+        
+        :param head: Head of the linked list
+        :return: List of values
+        """
+        result = []
+        current = head
+
+        while current:
+            result.append(current.val)
+            current = current.next
+
+        return result
+
+    def test_first_pattern(self):
+        # Input: list1 = [1,2,4], list2 = [1,3,4]
+        # Output: [1,1,2,3,4,4]
+        solution = Solution()
+        l1 = self.create_linked_list([1, 2, 4])
+        l2 = self.create_linked_list([1, 3, 4])
+        output = solution.mergeTwoLists(l1, l2)
+        result = self.linked_list_to_list(output)
+        target = [1, 1, 2, 3, 4, 4]
+        self.assertEqual(result, target)
+
+    def test_second_pattern(self):
+        # Input: list1 = [], list2 = []
+        # Output: []
+        solution = Solution()
+        l1 = self.create_linked_list([])
+        l2 = self.create_linked_list([])
+        output = solution.mergeTwoLists(l1, l2)
+        result = self.linked_list_to_list(output)
+        target = []
+        self.assertEqual(result, target)
+
+    def test_third_pattern(self):
+        # Input: list1 = [], list2 = [0]
+        # Output: [0]
+        solution = Solution()
+        l1 = self.create_linked_list([])
+        l2 = self.create_linked_list([0])
+        output = solution.mergeTwoLists(l1, l2)
+        result = self.linked_list_to_list(output)
+        target = [0]
+        self.assertEqual(result, target)