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Added task 3617 #2017

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109 changes: 109 additions & 0 deletions src/main/java/g3601_3700/s3617_find_students_with_study_spiral_pattern/readme.md
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3617\. Find Students with Study Spiral Pattern

Hard

Table: `students`

+--------------+---------+
| Column Name | Type |
+--------------+---------+
| student_id | int |
| student_name | varchar |
| major | varchar |
+--------------+---------+
student_id is the unique identifier for this table.
Each row contains information about a student and their academic major.

Table: `study_sessions`

+---------------+---------+
| Column Name | Type |
+---------------+---------+
| session_id | int |
| student_id | int |
| subject | varchar |
| session_date | date |
| hours_studied | decimal |
+---------------+---------+
session_id is the unique identifier for this table.
Each row represents a study session by a student for a specific subject.

Write a solution to find students who follow the **Study Spiral Pattern** - students who consistently study multiple subjects in a rotating cycle.

* A Study Spiral Pattern means a student studies at least `3` **different subjects** in a repeating sequence
* The pattern must repeat for **at least** `2` **complete cycles** (minimum `6` study sessions)
* Sessions must be **consecutive dates** with no gaps longer than `2` days between sessions
* Calculate the **cycle length** (number of different subjects in the pattern)
* Calculate the **total study hours** across all sessions in the pattern
* Only include students with cycle length of **at least** `3` **subjects**

Return _the result table ordered by cycle length in **descending** order, then by total study hours in **descending** order_.

The result format is in the following example.

**Example:**

**Input:**

students table:

| student_id | student_name | major |
|------------|--------------|-------------------|
| 1 | Alice Chen | Computer Science |
| 2 | Bob Johnson | Mathematics |
| 3 | Carol Davis | Physics |
| 4 | David Wilson | Chemistry |
| 5 | Emma Brown | Biology |

study\_sessions table:

| session_id | student_id | subject | session_date | hours_studied |
|------------|------------|------------|--------------|----------------|
| 1 | 1 | Math | 2023-10-01 | 2.5 |
| 2 | 1 | Physics | 2023-10-02 | 3.0 |
| 3 | 1 | Chemistry | 2023-10-03 | 2.0 |
| 4 | 1 | Math | 2023-10-04 | 2.5 |
| 5 | 1 | Physics | 2023-10-05 | 3.0 |
| 6 | 1 | Chemistry | 2023-10-06 | 2.0 |
| 7 | 2 | Algebra | 2023-10-01 | 4.0 |
| 8 | 2 | Calculus | 2023-10-02 | 3.5 |
| 9 | 2 | Statistics | 2023-10-03 | 2.5 |
| 10 | 2 | Geometry | 2023-10-04 | 3.0 |
| 11 | 2 | Algebra | 2023-10-05 | 4.0 |
| 12 | 2 | Calculus | 2023-10-06 | 3.5 |
| 13 | 2 | Statistics | 2023-10-07 | 2.5 |
| 14 | 2 | Geometry | 2023-10-08 | 3.0 |
| 15 | 3 | Biology | 2023-10-01 | 2.0 |
| 16 | 3 | Chemistry | 2023-10-02 | 2.5 |
| 17 | 3 | Biology | 2023-10-03 | 2.0 |
| 18 | 3 | Chemistry | 2023-10-04 | 2.5 |
| 19 | 4 | Organic | 2023-10-01 | 3.0 |
| 20 | 4 | Physical | 2023-10-05 | 2.5 |

**Output:**

| student_id | student_name | major | cycle_length | total_study_hours |
|------------|--------------|-------------------|--------------|-------------------|
| 2 | Bob Johnson | Mathematics | 4 | 26.0 |
| 1 | Alice Chen | Computer Science | 3 | 15.0 |

**Explanation:**

* **Alice Chen (student\_id = 1):**
* Study sequence: Math → Physics → Chemistry → Math → Physics → Chemistry
* Pattern: 3 subjects (Math, Physics, Chemistry) repeating for 2 complete cycles
* Consecutive dates: Oct 1-6 with no gaps > 2 days
* Cycle length: 3 subjects
* Total hours: 2.5 + 3.0 + 2.0 + 2.5 + 3.0 + 2.0 = 15.0 hours
* **Bob Johnson (student\_id = 2):**
* Study sequence: Algebra → Calculus → Statistics → Geometry → Algebra → Calculus → Statistics → Geometry
* Pattern: 4 subjects (Algebra, Calculus, Statistics, Geometry) repeating for 2 complete cycles
* Consecutive dates: Oct 1-8 with no gaps > 2 days
* Cycle length: 4 subjects
* Total hours: 4.0 + 3.5 + 2.5 + 3.0 + 4.0 + 3.5 + 2.5 + 3.0 = 26.0 hours
* **Students not included:**
* Carol Davis (student\_id = 3): Only 2 subjects (Biology, Chemistry) - doesn't meet minimum 3 subjects requirement
* David Wilson (student\_id = 4): Only 2 study sessions with a 4-day gap - doesn't meet consecutive dates requirement
* Emma Brown (student\_id = 5): No study sessions recorded

The result table is ordered by cycle\_length in descending order, then by total\_study\_hours in descending order.
122 changes: 122 additions & 0 deletions src/main/java/g3601_3700/s3617_find_students_with_study_spiral_pattern/script.sql
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# Write your MySQL query statement below
# #Hard #Database #2025_07_16_Time_553_ms_(100.00%)_Space_0.0_MB_(100.00%)
-- WITH studentstudysummary AS (
-- SELECT
-- student_id,
-- SUM(hours_studied) AS total_study_hours,
-- COUNT(DISTINCT subject) AS cycle_length
-- FROM
-- study_sessions
-- GROUP BY
-- student_id
-- HAVING
-- COUNT(DISTINCT subject) >= 3
-- ),
-- rankedstudysessionswithgaps AS (
-- SELECT
-- ss.student_id,
-- ss.subject,
-- ss.session_date,
-- DATEDIFF(
-- LEAD(ss.session_date, 1, ss.session_date)
-- OVER (PARTITION BY ss.student_id ORDER BY ss.session_date),
-- ss.session_date
-- ) AS gap_to_next_session,
-- ROW_NUMBER() OVER (PARTITION BY ss.student_id ORDER BY ss.session_date) AS rn,
-- sss.total_study_hours,
-- sss.cycle_length
-- FROM
-- study_sessions ss
-- INNER JOIN studentstudysummary sss
-- ON ss.student_id = sss.student_id
-- ),
-- cyclicstudents AS (
-- SELECT
-- rss1.student_id,
-- rss1.cycle_length,
-- rss1.total_study_hours
-- FROM
-- rankedstudysessionswithgaps rss1
-- INNER JOIN rankedstudysessionswithgaps rss2
-- ON rss1.student_id = rss2.student_id
-- AND rss2.rn = rss1.rn + rss1.cycle_length
-- AND rss1.subject = rss2.subject
-- WHERE
-- rss1.gap_to_next_session < 3
-- AND rss2.gap_to_next_session < 3
-- GROUP BY
-- rss1.student_id,
-- rss1.cycle_length,
-- rss1.total_study_hours
-- HAVING
-- COUNT(DISTINCT rss1.subject) >= 3
-- )
-- SELECT
-- s.student_id,
-- s.student_name,
-- s.major,
-- cs.cycle_length,
-- cs.total_study_hours
-- FROM
-- cyclicstudents cs
-- INNER JOIN students s
-- ON cs.student_id = s.student_id
-- ORDER BY
-- cs.cycle_length DESC,
-- cs.total_study_hours DESC;
WITH studentstudysummary AS (
SELECT
student_id,
SUM(hours_studied) AS total_study_hours,
COUNT(DISTINCT subject) AS cycle_length
FROM study_sessions
GROUP BY student_id
HAVING COUNT(DISTINCT subject) >= 3
),
rankedstudysessionswithgaps AS (
SELECT
ss.student_id,
ss.subject,
ss.session_date,
DATEDIFF('DAY',
ss.session_date,
LEAD(ss.session_date, 1, ss.session_date) OVER (
PARTITION BY ss.student_id ORDER BY ss.session_date
)
) AS gap_to_next_session,
ROW_NUMBER() OVER (PARTITION BY ss.student_id ORDER BY ss.session_date) AS rn,
sss.total_study_hours,
sss.cycle_length
FROM study_sessions ss
INNER JOIN studentstudysummary sss
ON ss.student_id = sss.student_id
),
cyclicstudents AS (
SELECT
rss1.student_id,
rss1.cycle_length,
rss1.total_study_hours
FROM rankedstudysessionswithgaps rss1
INNER JOIN rankedstudysessionswithgaps rss2
ON rss1.student_id = rss2.student_id
AND rss2.rn = rss1.rn + rss1.cycle_length
AND rss1.subject = rss2.subject
WHERE
rss1.gap_to_next_session < 3
AND rss2.gap_to_next_session < 3
GROUP BY
rss1.student_id,
rss1.cycle_length,
rss1.total_study_hours
HAVING
COUNT(DISTINCT rss1.subject) >= 3
)
SELECT
s.student_id,
s.student_name,
s.major,
cs.cycle_length,
cs.total_study_hours
FROM cyclicstudents cs
INNER JOIN students s ON cs.student_id = s.student_id
ORDER BY cs.cycle_length DESC, cs.total_study_hours DESC;
96 changes: 96 additions & 0 deletions src/test/java/g3601_3700/s3617_find_students_with_study_spiral_pattern/MysqlTest.java
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package g3601_3700.s3617_find_students_with_study_spiral_pattern;

import static org.hamcrest.CoreMatchers.equalTo;
import static org.hamcrest.MatcherAssert.assertThat;

import java.io.BufferedReader;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.stream.Collectors;
import javax.sql.DataSource;
import org.junit.jupiter.api.Test;
import org.zapodot.junit.db.annotations.EmbeddedDatabase;
import org.zapodot.junit.db.annotations.EmbeddedDatabaseTest;
import org.zapodot.junit.db.common.CompatibilityMode;

@EmbeddedDatabaseTest(
compatibilityMode = CompatibilityMode.MySQL,
initialSqls =
"CREATE TABLE students ("
+ " student_id INT PRIMARY KEY,"
+ " student_name VARCHAR(50),"
+ " major VARCHAR(50)"
+ ");"
+ "INSERT INTO students (student_id, student_name, major) VALUES"
+ "(1, 'Alice Chen', 'Computer Science'),"
+ "(2, 'Bob Johnson', 'Mathematics'),"
+ "(3, 'Carol Davis', 'Physics'),"
+ "(4, 'David Wilson', 'Chemistry'),"
+ "(5, 'Emma Brown', 'Biology');"
+ "CREATE TABLE study_sessions ("
+ " session_id INT PRIMARY KEY,"
+ " student_id INT,"
+ " subject VARCHAR(30),"
+ " session_date DATE,"
+ " hours_studied DECIMAL(3,1)"
+ ");"
+ "INSERT INTO study_sessions (session_id, student_id, "
+ "subject, session_date, hours_studied) VALUES"
+ "(1, 1, 'Math', '2023-10-01', 2.5),"
+ "(2, 1, 'Physics', '2023-10-02', 3.0),"
+ "(3, 1, 'Chemistry', '2023-10-03', 2.0),"
+ "(4, 1, 'Math', '2023-10-04', 2.5),"
+ "(5, 1, 'Physics', '2023-10-05', 3.0),"
+ "(6, 1, 'Chemistry', '2023-10-06', 2.0),"
+ "(7, 2, 'Algebra', '2023-10-01', 4.0),"
+ "(8, 2, 'Calculus', '2023-10-02', 3.5),"
+ "(9, 2, 'Statistics', '2023-10-03', 2.5),"
+ "(10, 2, 'Geometry', '2023-10-04', 3.0),"
+ "(11, 2, 'Algebra', '2023-10-05', 4.0),"
+ "(12, 2, 'Calculus', '2023-10-06', 3.5),"
+ "(13, 2, 'Statistics','2023-10-07', 2.5),"
+ "(14, 2, 'Geometry', '2023-10-08', 3.0),"
+ "(15, 3, 'Biology', '2023-10-01', 2.0),"
+ "(16, 3, 'Chemistry', '2023-10-02', 2.5),"
+ "(17, 3, 'Biology', '2023-10-03', 2.0),"
+ "(18, 3, 'Chemistry', '2023-10-04', 2.5),"
+ "(19, 4, 'Organic', '2023-10-01', 3.0),"
+ "(20, 4, 'Physical', '2023-10-05', 2.5);")
class MysqlTest {
@Test
void testScript(@EmbeddedDatabase DataSource dataSource)
throws SQLException, FileNotFoundException {
try (final Connection connection = dataSource.getConnection()) {
try (final Statement statement = connection.createStatement();
final ResultSet resultSet =
statement.executeQuery(
new BufferedReader(
new FileReader(
"src/main/java/g3601_3700/"
+ "s3617_find_students_with_"
+ "study_spiral_pattern/"
+ "script.sql"))
.lines()
.collect(Collectors.joining("\n"))
.replaceAll("#.*?\\r?\\n", ""))) {
assertThat(resultSet.next(), equalTo(true));
assertThat(resultSet.getNString(1), equalTo("2"));
assertThat(resultSet.getNString(2), equalTo("Bob Johnson"));
assertThat(resultSet.getNString(3), equalTo("Mathematics"));
assertThat(resultSet.getNString(4), equalTo("4"));
assertThat(resultSet.getNString(5), equalTo("26.0"));
assertThat(resultSet.next(), equalTo(true));
assertThat(resultSet.getNString(1), equalTo("1"));
assertThat(resultSet.getNString(2), equalTo("Alice Chen"));
assertThat(resultSet.getNString(3), equalTo("Computer Science"));
assertThat(resultSet.getNString(4), equalTo("3"));
assertThat(resultSet.getNString(5), equalTo("15.0"));
assertThat(resultSet.next(), equalTo(false));
}
}
}
}
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