摘要:
ID Course 1 AA 1 BB 2 AA 2 BB 2 CC 3 AA 3 BB 3 CC 3 DD 4 AA NULL NULL 选出选课数量>=2的学号 select distinct ID from test as A where (Select count(ID) from test 阅读全文
摘要:
题目: Given two integers n and k, return all possible combinations of k numbers out of 1 ... n. For example, If n = 4 and k = 2, a solution is: [ [2,4], 阅读全文