Human Traffic of Stadium

Author: ignacio-chiazzo

LeetcodeProblems/Databases/Human_Traffic_of_Stadium.sql

@@ -0,0 +1,57 @@
+/*
+Human Traffic of Stadium
+https://leetcode.com/problems/human-traffic-of-stadium/
+
+Table: Stadium
+
++---------------+---------+
+| Column Name   | Type    |
++---------------+---------+
+| id            | int     |
+| visit_date    | date    |
+| people        | int     |
++---------------+---------+
+visit_date is the primary key for this table.
+Each row of this table contains the visit date and visit id to the stadium with the number of people during the visit.
+No two rows will have the same visit_date, and as the id increases, the dates increase as well.
+
+Write an SQL query to display the records with three or more rows with consecutive id's, and the number of people is greater than or equal to 100 for each.
+
+Return the result table ordered by visit_date in ascending order.
+
+The query result format is in the following example.
+
+Stadium table:
++------+------------+-----------+
+| id   | visit_date | people    |
++------+------------+-----------+
+| 1    | 2017-01-01 | 10        |
+| 2    | 2017-01-02 | 109       |
+| 3    | 2017-01-03 | 150       |
+| 4    | 2017-01-04 | 99        |
+| 5    | 2017-01-05 | 145       |
+| 6    | 2017-01-06 | 1455      |
+| 7    | 2017-01-07 | 199       |
+| 8    | 2017-01-09 | 188       |
++------+------------+-----------+
+
+Result table:
++------+------------+-----------+
+| id   | visit_date | people    |
++------+------------+-----------+
+| 5    | 2017-01-05 | 145       |
+| 6    | 2017-01-06 | 1455      |
+| 7    | 2017-01-07 | 199       |
+| 8    | 2017-01-09 | 188       |
++------+------------+-----------+
+The four rows with ids 5, 6, 7, and 8 have consecutive ids and each of them has >= 100 people attended. Note that row 8 was included even though the visit_date was not the next day after row 7.
+The rows with ids 2 and 3 are not included because we need at least three consecutive ids.
+*/
+
+SELECT DISTINCT(s1.id) as id, s1.visit_date, s1.people
+FROM Stadium AS s1, Stadium AS s2, Stadium AS s3
+WHERE
+    (s1.people >= 100 AND s2.people >= 100 AND s3.people >= 100 AND s1.id = s2.id - 1 AND s2.id = s3.id - 1 AND s1.id = s3.id - 2) OR -- S1, S2, S3
+    (s1.people >= 100 AND s2.people >= 100 AND s3.people >= 100 AND s1.id = s2.id + 1 AND s2.id = s3.id - 2 AND s1.id = s3.id - 1) OR -- S2. S1. S3
+    (s1.people >= 100 AND s2.people >= 100 AND s3.people >= 100 AND s1.id = s2.id + 2 AND s2.id = s3.id - 1 AND s1.id = s3.id + 1)    -- S2 S3 S1
+ORDER BY s1.id ASC

README.md

@@ -81,7 +81,10 @@ To run a specific problem in your console, go to the file test, add the call to
 ### Databases
 | Problems | Level | Link |
 |-|-|-|
-| [Rank Scores](/LeetcodeProblems/Databases/Rank_Scores.sql) | Medium | https://leetcode.com/problems/rank-scores/ |
+Human Traffic of Stadium
+
+| [Human Traffic of Stadium](/LeetcodeProblems/Databases/Human_Traffic_of_Stadium.sql) | Hard | https://leetcode.com/problems/human-traffic-of-stadium |
+| [Rank Scores](/LeetcodeProblems/Databases/Rank_Scores.sql) | Medium | https://leetcode.com/problems/rank-scores |
 | [Consecutive Numbers](/LeetcodeProblems/Databases/Consecutive_Numbers.sql) | Medium | https://leetcode.com/problems/consecutive-numbers |
 | [Department Highest Salary](/LeetcodeProblems/Databases/Department_Highest_Salary.sql) | Medium | https://leetcode.com/problems/department-highest-salary |
 | [Exchange Seats](/LeetcodeProblems/Databases/Exchange_Seats.sql) | Medium | https://leetcode.com/problems/exchange-seats |