feat: add solutions to lc problem: No.3617

solution/3600-3699/3617.Find Students with Study Spiral Pattern/Solution.py

@@ -0,0 +1,97 @@
+import pandas as pd
+from datetime import timedelta
+
+
+def find_study_spiral_pattern(
+    students: pd.DataFrame, study_sessions: pd.DataFrame
+) -> pd.DataFrame:
+    # Convert session_date to datetime
+    study_sessions["session_date"] = pd.to_datetime(study_sessions["session_date"])
+
+    result = []
+
+    # Group study sessions by student
+    for student_id, group in study_sessions.groupby("student_id"):
+        # Sort sessions by date
+        group = group.sort_values("session_date").reset_index(drop=True)
+
+        temp = []  # Holds current contiguous segment
+        last_date = None
+
+        for idx, row in group.iterrows():
+            if not temp:
+                temp.append(row)
+            else:
+                delta = (row["session_date"] - last_date).days
+                if delta <= 2:
+                    temp.append(row)
+                else:
+                    # Check the previous contiguous segment
+                    if len(temp) >= 6:
+                        _check_pattern(student_id, temp, result)
+                    temp = [row]
+            last_date = row["session_date"]
+
+        # Check the final segment
+        if len(temp) >= 6:
+            _check_pattern(student_id, temp, result)
+
+    # Build result DataFrame
+    df_result = pd.DataFrame(
+        result, columns=["student_id", "cycle_length", "total_study_hours"]
+    )
+
+    if df_result.empty:
+        return pd.DataFrame(
+            columns=[
+                "student_id",
+                "student_name",
+                "major",
+                "cycle_length",
+                "total_study_hours",
+            ]
+        )
+
+    # Join with students table to get name and major
+    df_result = df_result.merge(students, on="student_id")
+
+    df_result = df_result[
+        ["student_id", "student_name", "major", "cycle_length", "total_study_hours"]
+    ]
+
+    return df_result.sort_values(
+        by=["cycle_length", "total_study_hours"], ascending=[False, False]
+    ).reset_index(drop=True)
+
+
+def _check_pattern(student_id, sessions, result):
+    subjects = [row["subject"] for row in sessions]
+    hours = sum(row["hours_studied"] for row in sessions)
+
+    n = len(subjects)
+
+    # Try possible cycle lengths from 3 up to half of the sequence
+    for cycle_len in range(3, n // 2 + 1):
+        if n % cycle_len != 0:
+            continue
+
+        # Extract the first cycle
+        first_cycle = subjects[:cycle_len]
+        is_pattern = True
+
+        # Compare each following cycle with the first
+        for i in range(1, n // cycle_len):
+            if subjects[i * cycle_len : (i + 1) * cycle_len] != first_cycle:
+                is_pattern = False
+                break
+
+        # If a repeated cycle is detected, store the result
+        if is_pattern:
+            result.append(
+                {
+                    "student_id": student_id,
+                    "cycle_length": cycle_len,
+                    "total_study_hours": hours,
+                }
+            )
+            break  # Stop at the first valid cycle found

solution/3600-3699/3617.Find Students with Study Spiral Pattern/Solution.sql

@@ -0,0 +1,150 @@
+# Write your MySQL query statement below
+WITH
+    ranked_sessions AS (
+        SELECT
+            s.student_id,
+            ss.session_date,
+            ss.subject,
+            ss.hours_studied,
+            ROW_NUMBER() OVER (
+                PARTITION BY s.student_id
+                ORDER BY ss.session_date
+            ) AS rn
+        FROM
+            study_sessions ss
+            JOIN students s ON s.student_id = ss.student_id
+    ),
+    grouped_sessions AS (
+        SELECT
+            *,
+            DATEDIFF(
+                session_date,
+                LAG(session_date) OVER (
+                    PARTITION BY student_id
+                    ORDER BY session_date
+                )
+            ) AS date_diff
+        FROM ranked_sessions
+    ),
+    session_groups AS (
+        SELECT
+            *,
+            SUM(
+                CASE
+                    WHEN date_diff > 2
+                    OR date_diff IS NULL THEN 1
+                    ELSE 0
+                END
+            ) OVER (
+                PARTITION BY student_id
+                ORDER BY session_date
+            ) AS group_id
+        FROM grouped_sessions
+    ),
+    valid_sequences AS (
+        SELECT
+            student_id,
+            group_id,
+            COUNT(*) AS session_count,
+            GROUP_CONCAT(subject ORDER BY session_date) AS subject_sequence,
+            SUM(hours_studied) AS total_hours
+        FROM session_groups
+        GROUP BY student_id, group_id
+        HAVING session_count >= 6
+    ),
+    pattern_detected AS (
+        SELECT
+            vs.student_id,
+            vs.total_hours,
+            vs.subject_sequence,
+            COUNT(
+                DISTINCT
+                SUBSTRING_INDEX(SUBSTRING_INDEX(subject_sequence, ',', n), ',', -1)
+            ) AS cycle_length
+        FROM
+            valid_sequences vs
+            JOIN (
+                SELECT a.N + b.N * 10 + 1 AS n
+                FROM
+                    (
+                        SELECT 0 AS N
+                        UNION
+                        SELECT 1
+                        UNION
+                        SELECT 2
+                        UNION
+                        SELECT 3
+                        UNION
+                        SELECT 4
+                        UNION
+                        SELECT 5
+                        UNION
+                        SELECT 6
+                        UNION
+                        SELECT 7
+                        UNION
+                        SELECT 8
+                        UNION
+                        SELECT 9
+                    ) a,
+                    (
+                        SELECT 0 AS N
+                        UNION
+                        SELECT 1
+                        UNION
+                        SELECT 2
+                        UNION
+                        SELECT 3
+                        UNION
+                        SELECT 4
+                        UNION
+                        SELECT 5
+                        UNION
+                        SELECT 6
+                        UNION
+                        SELECT 7
+                        UNION
+                        SELECT 8
+                        UNION
+                        SELECT 9
+                    ) b
+            ) nums
+                ON n <= 10
+        WHERE
+            -- Check if the sequence repeats every `k` items, for some `k >= 3` and divides session_count exactly
+            -- We simplify by checking the start and middle halves are equal
+            LENGTH(subject_sequence) > 0
+            AND LOCATE(',', subject_sequence) > 0
+            AND (
+                -- For cycle length 3:
+                subject_sequence LIKE CONCAT(
+                    SUBSTRING_INDEX(subject_sequence, ',', 3),
+                    ',',
+                    SUBSTRING_INDEX(SUBSTRING_INDEX(subject_sequence, ',', 6), ',', -3),
+                    '%'
+                )
+                OR subject_sequence LIKE CONCAT(
+                    -- For cycle length 4:
+                    SUBSTRING_INDEX(subject_sequence, ',', 4),
+                    ',',
+                    SUBSTRING_INDEX(SUBSTRING_INDEX(subject_sequence, ',', 8), ',', -4),
+                    '%'
+                )
+            )
+        GROUP BY vs.student_id, vs.total_hours, vs.subject_sequence
+    ),
+    final_output AS (
+        SELECT
+            s.student_id,
+            s.student_name,
+            s.major,
+            pd.cycle_length,
+            pd.total_hours AS total_study_hours
+        FROM
+            pattern_detected pd
+            JOIN students s ON s.student_id = pd.student_id
+        WHERE pd.cycle_length >= 3
+    )
+SELECT *
+FROM final_output
+ORDER BY cycle_length DESC, total_study_hours DESC;

solution/DATABASE_README.md

@@ -322,6 +322,7 @@
 | 3586 | [寻找 COVID 康复患者](/solution/3500-3599/3586.Find%20COVID%20Recovery%20Patients/README.md)                                                                 | `数据库` | 中等 |      |
 | 3601 | [寻找燃油效率提升的驾驶员](/solution/3600-3699/3601.Find%20Drivers%20with%20Improved%20Fuel%20Efficiency/README.md)                                          | `数据库` | 中等 |      |
 | 3611 | [查找超预订员工](/solution/3600-3699/3611.Find%20Overbooked%20Employees/README.md)                                                                           |          | 中等 |      |
+| 3617 | [Find Students with Study Spiral Pattern](/solution/3600-3699/3617.Find%20Students%20with%20Study%20Spiral%20Pattern/README.md)                              |          | 困难 |      |
 
 ## 版权
 

solution/DATABASE_README_EN.md

@@ -320,6 +320,7 @@ Press <kbd>Control</kbd> + <kbd>F</kbd>(or <kbd>Command</kbd> + <kbd>F</kbd> on
 | 3586 | [Find COVID Recovery Patients](/solution/3500-3599/3586.Find%20COVID%20Recovery%20Patients/README_EN.md)                                                                                     | `Database` | Medium     |        |
 | 3601 | [Find Drivers with Improved Fuel Efficiency](/solution/3600-3699/3601.Find%20Drivers%20with%20Improved%20Fuel%20Efficiency/README_EN.md)                                                     | `Database` | Medium     |        |
 | 3611 | [Find Overbooked Employees](/solution/3600-3699/3611.Find%20Overbooked%20Employees/README_EN.md)                                                                                             |            | Medium     |        |
+| 3617 | [Find Students with Study Spiral Pattern](/solution/3600-3699/3617.Find%20Students%20with%20Study%20Spiral%20Pattern/README_EN.md)                                                           |            | Hard       |        |
 
 ## Copyright
 

solution/README.md

@@ -3627,6 +3627,7 @@
 |  3614  |  [用特殊操作处理字符串 II](/solution/3600-3699/3614.Process%20String%20with%20Special%20Operations%20II/README.md)  |    |  困难  |  第 458 场周赛  |
 |  3615  |  [图中的最长回文路径](/solution/3600-3699/3615.Longest%20Palindromic%20Path%20in%20Graph/README.md)  |    |  困难  |  第 458 场周赛  |
 |  3616  |  [Number of Student Replacements](/solution/3600-3699/3616.Number%20of%20Student%20Replacements/README.md)  |    |  中等  |  🔒  |
+|  3617  |  [Find Students with Study Spiral Pattern](/solution/3600-3699/3617.Find%20Students%20with%20Study%20Spiral%20Pattern/README.md)  |    |  困难  |    |
 
 ## 版权
 

solution/README_EN.md

@@ -3625,6 +3625,7 @@ Press <kbd>Control</kbd> + <kbd>F</kbd>(or <kbd>Command</kbd> + <kbd>F</kbd> on
 |  3614  |  [Process String with Special Operations II](/solution/3600-3699/3614.Process%20String%20with%20Special%20Operations%20II/README_EN.md)  |    |  Hard  |  Weekly Contest 458  |
 |  3615  |  [Longest Palindromic Path in Graph](/solution/3600-3699/3615.Longest%20Palindromic%20Path%20in%20Graph/README_EN.md)  |    |  Hard  |  Weekly Contest 458  |
 |  3616  |  [Number of Student Replacements](/solution/3600-3699/3616.Number%20of%20Student%20Replacements/README_EN.md)  |    |  Medium  |  🔒  |
+|  3617  |  [Find Students with Study Spiral Pattern](/solution/3600-3699/3617.Find%20Students%20with%20Study%20Spiral%20Pattern/README_EN.md)  |    |  Hard  |    |
 
 ## Copyright