feat: add Merge Intervals

Author: wislertt

.templates/leetcode/json/merge_intervals.json

@@ -0,0 +1,50 @@
+{
+    "problem_name": "merge_intervals",
+    "solution_class_name": "Solution",
+    "problem_number": "56",
+    "problem_title": "Merge Intervals",
+    "difficulty": "Medium",
+    "topics": "Array, Sorting",
+    "tags": ["grind-75"],
+    "readme_description": "Given an array of `intervals` where `intervals[i] = [starti, endi]`, merge all overlapping intervals, and return an array of the non-overlapping intervals that cover all the intervals in the input.",
+    "readme_examples": [
+        {
+            "content": "```\nInput: intervals = [[1,3],[2,6],[8,10],[15,18]]\nOutput: [[1,6],[8,10],[15,18]]\n```\n**Explanation:** Since intervals [1,3] and [2,6] overlap, merge them into [1,6]."
+        },
+        {
+            "content": "```\nInput: intervals = [[1,4],[4,5]]\nOutput: [[1,5]]\n```\n**Explanation:** Intervals [1,4] and [4,5] are considered overlapping."
+        },
+        {
+            "content": "```\nInput: intervals = [[4,7],[1,4]]\nOutput: [[1,7]]\n```\n**Explanation:** Intervals [1,4] and [4,7] are considered overlapping."
+        }
+    ],
+    "readme_constraints": "- `1 <= intervals.length <= 10^4`\n- `intervals[i].length == 2`\n- `0 <= starti <= endi <= 10^4`",
+    "readme_additional": "",
+    "solution_imports": "",
+    "solution_methods": [
+        {
+            "name": "merge",
+            "parameters": "intervals: list[list[int]]",
+            "return_type": "list[list[int]]",
+            "dummy_return": "[]"
+        }
+    ],
+    "test_imports": "import pytest\nfrom leetcode_py.test_utils import logged_test\nfrom .solution import Solution",
+    "test_class_name": "MergeIntervals",
+    "test_helper_methods": [
+        { "name": "setup_method", "parameters": "", "body": "self.solution = Solution()" }
+    ],
+    "test_methods": [
+        {
+            "name": "test_merge",
+            "parametrize": "intervals, expected",
+            "parametrize_typed": "intervals: list[list[int]], expected: list[list[int]]",
+            "test_cases": "[([[1,3],[2,6],[8,10],[15,18]], [[1,6],[8,10],[15,18]]), ([[1,4],[4,5]], [[1,5]]), ([[4,7],[1,4]], [[1,7]])]",
+            "body": "result = self.solution.merge(intervals)\nassert result == expected"
+        }
+    ],
+    "playground_imports": "from solution import Solution",
+    "playground_test_case": "# Example test case\nintervals = [[1,3],[2,6],[8,10],[15,18]]\nexpected = [[1,6],[8,10],[15,18]]",
+    "playground_execution": "result = Solution().merge(intervals)\nresult",
+    "playground_assertion": "assert result == expected"
+}

Makefile

@@ -1,5 +1,5 @@
 PYTHON_VERSION = 3.13
-PROBLEM ?= longest_palindrome
+PROBLEM ?= merge_intervals
 FORCE ?= 0
 COMMA := ,
 

leetcode/merge_intervals/README.md

@@ -0,0 +1,46 @@
+# Merge Intervals
+
+**Difficulty:** Medium
+**Topics:** Array, Sorting
+**Tags:** grind-75
+
+**LeetCode:** [Problem 56](https://leetcode.com/problems/merge-intervals/description/)
+
+## Problem Description
+
+Given an array of `intervals` where `intervals[i] = [starti, endi]`, merge all overlapping intervals, and return an array of the non-overlapping intervals that cover all the intervals in the input.
+
+## Examples
+
+### Example 1:
+
+```
+Input: intervals = [[1,3],[2,6],[8,10],[15,18]]
+Output: [[1,6],[8,10],[15,18]]
+```
+
+**Explanation:** Since intervals [1,3] and [2,6] overlap, merge them into [1,6].
+
+### Example 2:
+
+```
+Input: intervals = [[1,4],[4,5]]
+Output: [[1,5]]
+```
+
+**Explanation:** Intervals [1,4] and [4,5] are considered overlapping.
+
+### Example 3:
+
+```
+Input: intervals = [[4,7],[1,4]]
+Output: [[1,7]]
+```
+
+**Explanation:** Intervals [1,4] and [4,7] are considered overlapping.
+
+## Constraints
+
+- `1 <= intervals.length <= 10^4`
+- `intervals[i].length == 2`
+- `0 <= starti <= endi <= 10^4`

leetcode/merge_intervals/__init__.py

@@ -0,0 +1,67 @@
+{
+ "cells": [
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "imports",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "from solution import Solution"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "setup",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "# Example test case\n",
+    "intervals = [[1, 3], [2, 6], [8, 10], [15, 18]]\n",
+    "expected = [[1, 6], [8, 10], [15, 18]]"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "execute",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "result = Solution().merge(intervals)\nresult"
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "id": "test",
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "assert result == expected"
+   ]
+  }
+ ],
+ "metadata": {
+  "kernelspec": {
+   "display_name": "leetcode-py-py3.13",
+   "language": "python",
+   "name": "python3"
+  },
+  "language_info": {
+   "codemirror_mode": {
+    "name": "ipython",
+    "version": 3
+   },
+   "file_extension": ".py",
+   "mimetype": "text/x-python",
+   "name": "python",
+   "nbconvert_exporter": "python3",
+   "pygments_lexer": "ipython3",
+   "version": "3.13.7"
+  }
+ },
+ "nbformat": 4,
+ "nbformat_minor": 5
+}

leetcode/merge_intervals/playground.ipynb

@@ -0,0 +1,14 @@
+class Solution:
+    # Time: O(n log n)
+    # Space: O(1)
+    def merge(self, intervals: list[list[int]]) -> list[list[int]]:
+        intervals.sort()
+        merged = [intervals[0]]
+
+        for start, end in intervals[1:]:
+            if start <= merged[-1][1]:
+                merged[-1][1] = max(merged[-1][1], end)
+            else:
+                merged.append([start, end])
+
+        return merged

leetcode/merge_intervals/solution.py

@@ -0,0 +1,32 @@
+import pytest
+
+from leetcode_py.test_utils import logged_test
+
+from .solution import Solution
+
+
+class TestMergeIntervals:
+    def setup_method(self):
+        self.solution = Solution()
+
+    @pytest.mark.parametrize(
+        "intervals, expected",
+        [
+            # Original test cases
+            ([[1, 3], [2, 6], [8, 10], [15, 18]], [[1, 6], [8, 10], [15, 18]]),
+            ([[1, 4], [4, 5]], [[1, 5]]),
+            ([[4, 7], [1, 4]], [[1, 7]]),
+            # Edge cases
+            ([[1, 1]], [[1, 1]]),  # Single point interval
+            ([[1, 2], [3, 4]], [[1, 2], [3, 4]]),  # No overlap
+            ([[1, 4], [2, 3]], [[1, 4]]),  # Complete overlap
+            ([[1, 10], [2, 6], [8, 10], [15, 18]], [[1, 10], [15, 18]]),  # Multiple merges
+            ([[0, 0], [1, 1], [2, 2]], [[0, 0], [1, 1], [2, 2]]),  # All single points
+            ([[1, 3], [2, 6], [8, 10], [9, 12], [15, 18]], [[1, 6], [8, 12], [15, 18]]),  # Chain merge
+            ([[4, 5], [4, 6]], [[4, 6]]),  # Same start time
+        ],
+    )
+    @logged_test
+    def test_merge(self, intervals: list[list[int]], expected: list[list[int]]):
+        result = self.solution.merge(intervals)
+        assert result == expected