摘要：1 def isValid(s): 2 if s and len(s) % 2 is 0: 3 a = {')': '(', ']': '[', '}': '{'} 4 l = [None] 5 for i in s: 6 if i in a and a[i] == l[-1]: 7 ... 阅读全文

摘要：1、 第二高的薪水 select ifnull((select distinct Salary from Employee order by Salary desc limit 1,1),null) as SecondHighestSalary; 2、第N高的薪水 select distinct S 阅读全文

摘要：直接上代码： 阅读全文