leetcode-problemset/leetcode-cn/originData/most-common-course-pairs.json

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        "question": {
            "questionId": "4169",
            "questionFrontendId": "3764",
            "categoryTitle": "Database",
            "boundTopicId": 3848456,
            "title": "Most Common Course Pairs",
            "titleSlug": "most-common-course-pairs",
            "content": "<p>Table: <code>course_completions</code></p>\n\n<pre>\n+-------------------+---------+\n| Column Name       | Type    | \n+-------------------+---------+\n| user_id           | int     |\n| course_id         | int     |\n| course_name       | varchar |\n| completion_date   | date    |\n| course_rating     | int     |\n+-------------------+---------+\n(user_id, course_id) is the combination of columns with unique values for this table.\nEach row represents a completed course by a user with their rating (1-5 scale).\n</pre>\n\n<p>Write a solution to identify <strong>skill mastery pathways</strong> by analyzing course completion sequences among top-performing students:</p>\n\n<ul>\n\t<li>Consider only <strong>top-performing students</strong> (those who completed <strong>at least </strong><code>5</code><strong> courses</strong> with an <strong>average rating of </strong><code>4</code><strong> or higher</strong>).</li>\n\t<li>For each top performer, identify the <strong>sequence of courses</strong> they completed in chronological order.</li>\n\t<li>Find all <strong>consecutive course pairs</strong> (<code>Course A &rarr; Course B</code>) taken by these students.</li>\n\t<li>Return the <strong>pair frequency</strong>, identifying which course transitions are most common among high achievers.</li>\n</ul>\n\n<p>Return <em>the result table ordered by</em> <em>pair frequency in <strong>descending</strong> order</em>&nbsp;<em>and then by first course name and second course name in <strong>ascending</strong> order</em>.</p>\n\n<p>The result format is in the following example.</p>\n\n<p>&nbsp;</p>\n<p><strong class=\"example\">Example:</strong></p>\n\n<div class=\"example-block\">\n<p><strong>Input:</strong></p>\n\n<p>course_completions table:</p>\n\n<pre class=\"example-io\">\n+---------+-----------+------------------+-----------------+---------------+\n| user_id | course_id | course_name      | completion_date | course_rating |\n+---------+-----------+------------------+-----------------+---------------+\n| 1       | 101       | Python Basics    | 2024-01-05      | 5             |\n| 1       | 102       | SQL Fundamentals | 2024-02-10      | 4             |\n| 1       | 103       | JavaScript       | 2024-03-15      | 5             |\n| 1       | 104       | React Basics     | 2024-04-20      | 4             |\n| 1       | 105       | Node.js          | 2024-05-25      | 5             |\n| 1       | 106       | Docker           | 2024-06-30      | 4             |\n| 2       | 101       | Python Basics    | 2024-01-08      | 4             |\n| 2       | 104       | React Basics     | 2024-02-14      | 5             |\n| 2       | 105       | Node.js          | 2024-03-20      | 4             |\n| 2       | 106       | Docker           | 2024-04-25      | 5             |\n| 2       | 107       | AWS Fundamentals | 2024-05-30      | 4             |\n| 3       | 101       | Python Basics    | 2024-01-10      | 3             |\n| 3       | 102       | SQL Fundamentals | 2024-02-12      | 3             |\n| 3       | 103       | JavaScript       | 2024-03-18      | 3             |\n| 3       | 104       | React Basics     | 2024-04-22      | 2             |\n| 3       | 105       | Node.js          | 2024-05-28      | 3             |\n| 4       | 101       | Python Basics    | 2024-01-12      | 5             |\n| 4       | 108       | Data Science     | 2024-02-16      | 5             |\n| 4       | 109       | Machine Learning | 2024-03-22      | 5             |\n+---------+-----------+------------------+-----------------+---------------+\n</pre>\n\n<p><strong>Output:</strong></p>\n\n<pre class=\"example-io\">\n+------------------+------------------+------------------+\n| first_course     | second_course    | transition_count |\n+------------------+------------------+------------------+\n| Node.js          | Docker           | 2                |\n| React Basics     | Node.js          | 2                |\n| Docker           | AWS Fundamentals | 1                |\n| JavaScript       | React Basics     | 1                |\n| Python Basics    | React Basics     | 1                |\n| Python Basics    | SQL Fundamentals | 1                |\n| SQL Fundamentals | JavaScript       | 1                |\n+------------------+------------------+------------------+\n</pre>\n\n<p><strong>Explanation:</strong></p>\n\n<ul>\n\t<li><strong>User 1</strong>: Completed 6 courses with average rating 4.5 (qualifies as top performer)</li>\n\t<li><strong>User 2</strong>: Completed 5 courses with average rating 4.4 (qualifies as top performer)</li>\n\t<li><strong>User 3</strong>: Completed 5 courses but average rating is 2.8 (does not qualify)</li>\n\t<li><strong>User 4</strong>: Completed only 3 courses (does not qualify)</li>\n\t<li><strong>Course Pairs Among Top Performers</strong>:\n\t<ul>\n\t\t<li>User 1: Python Basics &rarr; SQL Fundamentals &rarr; JavaScript &rarr; React Basics &rarr; Node.js &rarr; Docker</li>\n\t\t<li>User 2: Python Basics &rarr; React Basics &rarr; Node.js &rarr; Docker &rarr; AWS Fundamentals</li>\n\t\t<li>Most common transitions: Node.js &rarr; Docker (2 times), React Basics &rarr; Node.js (2 times)</li>\n\t</ul>\n\t</li>\n</ul>\n\n<p>Results are ordered by transition_count in descending order, then by first_course in ascending order, and then by second_course in ascending order.</p>\n</div>\n",
            "translatedTitle": "最常见的课程组合",
            "translatedContent": "<p>表：<code>course_completions</code></p>\n\n<pre>\n+-------------------+---------+\n| Column Name       | Type    | \n+-------------------+---------+\n| user_id           | int     |\n| course_id         | int     |\n| course_name       | varchar |\n| completion_date   | date    |\n| course_rating     | int     |\n+-------------------+---------+\n(user_id, course_id) 是此表中具有不同值的列的组合。\n每一行代表一个用户完成的课程及其评分（1-5 分）。\n</pre>\n\n<p>编写一个解决方案，通过分析顶尖学生完成课程的序列来识别 <strong>课程路径</strong>：</p>\n\n<ul>\n\t<li>只考虑 <strong>顶尖学生</strong>（完成 <strong>至少</strong> <code>5</code> <strong>门课程且平均评分</strong> <code>4</code> <strong>分或以上&nbsp;</strong>的人）。</li>\n\t<li>对每个顶尖学生，确定他们按时间顺序完成的 <strong>课程序列</strong>。</li>\n\t<li>找出这些学生所学的所有 <strong>连续课程对&nbsp;</strong>（<code>课程 A → 课程 B</code>）。</li>\n\t<li>返回课程对的频率，确定顶尖学生中最常见的课程路径。</li>\n</ul>\n\n<p>返回结果表，按课程对频率 <strong>降序</strong> 排列，若频率相同则按第一课程名称和第二课程名称 <strong>升序</strong> 排列。</p>\n\n<p>结果格式如下所示。</p>\n\n<p>&nbsp;</p>\n\n<p><strong class=\"example\">示例：</strong></p>\n\n<div class=\"example-block\">\n<p><strong>输入：</strong></p>\n\n<p>course_completions 表：</p>\n\n<pre class=\"example-io\">\n+---------+-----------+------------------+-----------------+---------------+\n| user_id | course_id | course_name      | completion_date | course_rating |\n+---------+-----------+------------------+-----------------+---------------+\n| 1       | 101       | Python Basics    | 2024-01-05      | 5             |\n| 1       | 102       | SQL Fundamentals | 2024-02-10      | 4             |\n| 1       | 103       | JavaScript       | 2024-03-15      | 5             |\n| 1       | 104       | React Basics     | 2024-04-20      | 4             |\n| 1       | 105       | Node.js          | 2024-05-25      | 5             |\n| 1       | 106       | Docker           | 2024-06-30      | 4             |\n| 2       | 101       | Python Basics    | 2024-01-08      | 4             |\n| 2       | 104       | React Basics     | 2024-02-14      | 5             |\n| 2       | 105       | Node.js          | 2024-03-20      | 4             |\n| 2       | 106       | Docker           | 2024-04-25      | 5             |\n| 2       | 107       | AWS Fundamentals | 2024-05-30      | 4             |\n| 3       | 101       | Python Basics    | 2024-01-10      | 3             |\n| 3       | 102       | SQL Fundamentals | 2024-02-12      | 3             |\n| 3       | 103       | JavaScript       | 2024-03-18      | 3             |\n| 3       | 104       | React Basics     | 2024-04-22      | 2             |\n| 3       | 105       | Node.js          | 2024-05-28      | 3             |\n| 4       | 101       | Python Basics    | 2024-01-12      | 5             |\n| 4       | 108       | Data Science     | 2024-02-16      | 5             |\n| 4       | 109       | Machine Learning | 2024-03-22      | 5             |\n+---------+-----------+------------------+-----------------+---------------+\n</pre>\n\n<p><strong>输出：</strong></p>\n\n<pre class=\"example-io\">\n+------------------+------------------+------------------+\n| first_course     | second_course    | transition_count |\n+------------------+------------------+------------------+\n| Node.js          | Docker           | 2                |\n| React Basics     | Node.js          | 2                |\n| Docker           | AWS Fundamentals | 1                |\n| JavaScript       | React Basics     | 1                |\n| Python Basics    | React Basics     | 1                |\n| Python Basics    | SQL Fundamentals | 1                |\n| SQL Fundamentals | JavaScript       | 1                |\n+------------------+------------------+------------------+\n</pre>\n\n<p><strong>解释：</strong></p>\n\n<ul>\n\t<li><strong>用户 1：</strong>完成了 6 门课程，平均分为 4.5（满足顶尖学生）</li>\n\t<li><strong>用户 2：</strong>完成了 5 门课程，平均分为 4.4（满足顶尖学生）</li>\n\t<li><strong>用户 3：</strong>完成了 5 门课程但平均得分为 2.8（不满足资格）</li>\n\t<li><strong>用户 4：</strong>只完成了 3 门课程（不满足资格）</li>\n\t<li><strong>顶尖学生的课程对：</strong>\n\t<ul>\n\t\t<li>用户 1：Python Basics → SQL Fundamentals → JavaScript → React Basics → Node.js → Docker</li>\n\t\t<li>用户 2：Python Basics → React Basics → Node.js → Docker → AWS Fundamentals</li>\n\t\t<li>最常见的路径：Node.js → Docker (2 次)，React Basics → Node.js (2 次)</li>\n\t</ul>\n\t</li>\n</ul>\n\n<p>结果按 transition_count 降序排列，然后按 first_course 升序排列，再按 second_course 升序排列。</p>\n</div>\n",
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                "insert into course_completions (user_id, course_id, course_name, completion_date, course_rating) values ('1', '101', 'Python Basics', '2024-01-05', '5')",
                "insert into course_completions (user_id, course_id, course_name, completion_date, course_rating) values ('1', '102', 'SQL Fundamentals', '2024-02-10', '4')",
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                "insert into course_completions (user_id, course_id, course_name, completion_date, course_rating) values ('3', '102', 'SQL Fundamentals', '2024-02-12', '3')",
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                "insert into course_completions (user_id, course_id, course_name, completion_date, course_rating) values ('3', '105', 'Node.js', '2024-05-28', '3')",
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                "insert into course_completions (user_id, course_id, course_name, completion_date, course_rating) values ('4', '109', 'Machine Learning', '2024-03-22', '5')"
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