feat: add more leetcode problems

Author: wisarootl

.cursor/.dev/1-update-cookiecutter-test-template.md

@@ -1,5 +1,5 @@
 PYTHON_VERSION = 3.13
-PROBLEM ?= palindromic_substrings
+PROBLEM ?= reverse_nodes_in_k_group
 FORCE ?= 0
 COMMA := ,
 

Makefile

@@ -40,13 +40,13 @@ A Python package to generate professional LeetCode practice environments. Featur
 
 **Current Problem Sets**:
 
-- **grind-75** (75 problems) - Essential coding interview questions from [Grind 75](https://www.techinterviewhandbook.org/grind75/) ✅ Complete
-- **grind** (100+ problems) - Extended Grind collection including all Grind 75 plus additional problems 🚧 Partial
-- **blind-75** (75 problems) - Original [Blind 75](https://leetcode.com/problem-list/xi4ci4ig/) curated list 🚧 Partial
-- **neetcode-150** (150+ problems) - Comprehensive [NeetCode 150](https://neetcode.io/practice) problem set 🚧 Partial
-- **algo-master-75** (75 problems) - Curated algorithmic mastery problems 🚧 Partial
+- **grind-75** - Essential coding interview questions from [Grind 75](https://www.techinterviewhandbook.org/grind75/) ✅ Complete
+- **grind** - Extended Grind collection including all Grind 75 plus additional problems 🚧 Partial
+- **blind-75** - Original [Blind 75](https://leetcode.com/problem-list/xi4ci4ig/) curated list 🚧 Partial
+- **neetcode-150** - Comprehensive [NeetCode 150](https://neetcode.io/practice) problem set 🚧 Partial
+- **algo-master-75** - Curated algorithmic mastery problems 🚧 Partial
 
-**Coverage**: 100+ unique problems across all major coding interview topics and difficulty levels.
+**Coverage**: 120+ unique problems across all major coding interview topics and difficulty levels.
 
 **Note**: Some problem sets are partially covered. We're actively working to complete all collections. [Contributions welcome!](https://github.com/wisarootl/leetcode-py/blob/main/CONTRIBUTING.md)
 

README.md

@@ -0,0 +1,45 @@
+# Add Two Numbers
+
+**Difficulty:** Medium
+**Topics:** Linked List, Math, Recursion
+**Tags:** algo-master-75
+
+**LeetCode:** [Problem 2](https://leetcode.com/problems/add-two-numbers/description/)
+
+## Problem Description
+
+You are given two **non-empty** linked lists representing two non-negative integers. The digits are stored in **reverse order**, and each of their nodes contains a single digit. Add the two numbers and return the sum as a linked list.
+
+You may assume the two numbers do not contain any leading zero, except the number 0 itself.
+
+## Examples
+
+### Example 1:
+
+![Example 1](https://assets.leetcode.com/uploads/2020/10/02/addtwonumber1.jpg)
+
+```
+Input: l1 = [2,4,3], l2 = [5,6,4]
+Output: [7,0,8]
+Explanation: 342 + 465 = 807.
+```
+
+### Example 2:
+
+```
+Input: l1 = [0], l2 = [0]
+Output: [0]
+```
+
+### Example 3:
+
+```
+Input: l1 = [9,9,9,9,9,9,9], l2 = [9,9,9,9]
+Output: [8,9,9,9,0,0,0,1]
+```
+
+## Constraints
+
+- The number of nodes in each linked list is in the range [1, 100].
+- 0 <= Node.val <= 9
+- It is guaranteed that the list represents a number that does not have leading zeros.

leetcode/add_two_numbers/README.md

@@ -0,0 +1,14 @@
+from leetcode_py import ListNode
+
+
+def run_add_two_numbers(solution_class: type, l1_vals: list[int], l2_vals: list[int]):
+    l1 = ListNode.from_list(l1_vals)
+    l2 = ListNode.from_list(l2_vals)
+    implementation = solution_class()
+    return implementation.add_two_numbers(l1, l2)
+
+
+def assert_add_two_numbers(result: ListNode[int] | None, expected_vals: list[int]) -> bool:
+    expected = ListNode.from_list(expected_vals)
+    assert result == expected
+    return True

leetcode/add_two_numbers/__init__.py

@@ -0,0 +1,30 @@
+# ---
+# jupyter:
+#   jupytext:
+#     text_representation:
+#       extension: .py
+#       format_name: percent
+#       format_version: '1.3'
+#       jupytext_version: 1.17.3
+#   kernelspec:
+#     display_name: leetcode-py-py3.13
+#     language: python
+#     name: python3
+# ---
+
+# %%
+from helpers import assert_add_two_numbers, run_add_two_numbers
+from solution import Solution
+
+# %%
+# Example test case
+l1_vals = [2, 4, 3]
+l2_vals = [5, 6, 4]
+expected_vals = [7, 0, 8]
+
+# %%
+result = run_add_two_numbers(Solution, l1_vals, l2_vals)
+result
+
+# %%
+assert_add_two_numbers(result, expected_vals)

leetcode/add_two_numbers/helpers.py

@@ -0,0 +1,27 @@
+from leetcode_py import ListNode
+
+
+class Solution:
+
+    # Time: O(max(m, n))
+    # Space: O(max(m, n))
+    def add_two_numbers(
+        self, l1: ListNode[int] | None, l2: ListNode[int] | None
+    ) -> ListNode[int] | None:
+        dummy = ListNode(0)
+        current = dummy
+        carry = 0
+
+        while l1 or l2 or carry:
+            val1 = l1.val if l1 else 0
+            val2 = l2.val if l2 else 0
+
+            total = val1 + val2 + carry
+            carry = total // 10
+            current.next = ListNode(total % 10)
+            current = current.next
+
+            l1 = l1.next if l1 else None
+            l2 = l2.next if l2 else None
+
+        return dummy.next