【leetcode database】Human Traffic of Stadium
阿新 • • 發佈:2017-06-26
bsp col eight new where date lease data class
X city built a new stadium, each day many people visit it and the stats are saved as these columns: id, date, people Please write a query to display the records which have 3 or more consecutive rows and the amount of people more than 100(inclusive). For example, the table stadium: +------+------------+-----------+ | id | 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 | 2017-01-08 | 188 | +------+------------+-----------+ For the sample data above, the output is: +------+------------+-----------+ | id | date | people | +------+------------+-----------+ | 5 | 2017-01-05 | 145 | | 6 | 2017-01-06 | 1455 | | 7 | 2017-01-07 | 199 | | 8 | 2017-01-08 | 188 | +------+------------+-----------+ Note: Each day only have one row record, and the dates are increasing with id increasing.
這題的難度屬於hard級別,但我覺得最多也就是一般難度。初看起來這題好像有點不知所措,但仔細分析卻能發現其實條件很簡單,只要滿足以下任意三個條件即可:
1.id in (x,x+1,x+2) 的記錄的people >= 100;
2.1.id in (x,x+1,x-1) 的記錄的people >= 100;
3.1.id in (x,x-1,x-2) 的記錄的people >= 100;
代碼如下:
select * from stadium a where a.people >= 100 and ( ( a.id+1 in (select id from stadium wherepeople >= 100) and a.id+2 in (select id from stadium where people >= 100) ) or ( a.id-1 in (select id from stadium where people >= 100) and a.id+1 in (select id from stadium where people >= 100) ) or ( a.id-1 in (select id from stadium where people >= 100) and a.id-2 in (selectid from stadium where people >= 100) ) );
【leetcode database】Human Traffic of Stadium