Given scores of N athletes, find their relative ranks and the people with the top three highest scores, who will be awarded medals: “Gold Medal”, “Sil ...

Given an integer, return its base 7 string representation. ExampleNo.1Input: 100 Output: “202” No.2Input: -7 Output: “-10” NoteThe input will be in ra ...

集合运算的几个注意事项顾名思义，集合运算符的参数是集合，从数据库实现层面上来说就是表或者视图。 SQL能操作具有重复行的集合，可以通过可选项ALL来支持 集合运算符为了排除掉重复行，默认地会发生排序，而加上可选项ALL之后，就不会再排序，所以性能会有提升。 集合运算符有优先级 INTE ...

For a web developer, it is very important to know how to design a web page’s size. So, given a specific rectangular web page’s area, your job by now i ...

You are given a license key represented as a string S which consists only alphanumeric character and dashes. The string is separated into N+1 groups b ...

Winter is coming! Your first job during the contest is to design a standard heater with fixed warm radius to warm all the houses. Now, you are given p ...

关联子查询是一种非常强大的运算，也有一些它的缺点。第一个缺点是代码的可读性不好。第二个缺点是性能不好。特别是在SELECT子句里使用标量子查询时，性能可能会变差。 增长、减少、维持现状假设有下面这样一张记录了某个公司每年的营业额的表Sales。 根据这张表里的数据，使用SQL输出与上一年相比营业额 ...

用外连接进行行列转换（1）（行->列）：制作交叉表这里有一张用于管理员工学习过的培训课程的表，如下所示。 利用上面这张表生成下面这样一张交叉表（“课程学习记录一览表”）。 123456789-- 外连接SELECT C0.name, CASE WHEN C1.name IS N ...

Given a non-empty string check if it can be constructed by taking a substring of it and appending multiple copies of the substring together. You may a ...

Assume you are an awesome parent and want to give your children some cookies. But, you should give each child at most one cookie. Each child i has a g ...