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题解 | #判断链表中是否有环#

/** * Definition for singly-linked list. * class ListNode { * int val; * ListNode next; ...

Java

2022-05-28

1 251

题解 | #合并两个排序的链表#

/* public class ListNode { int val; ListNode next = null; ListNode(int val) { t...

Java

2022-05-28

1 323

题解 | #链表内指定区间反转#

import java.util.*; /* * public class ListNode { * int val; * ListNode next = null; * } */ pub...

Java

2022-05-28

1 365

题解 | #反转链表#

/* public class ListNode { int val; ListNode next = null; ListNode(int val) { t...

Java

2022-05-28

1 267

题解 | #插入记录（一）#

insert into exam_record values(null,1001,9001,'2021-09-01 22:11:12','2021-09-01 23:01:12',90), (null,1002,9002,'2021-09-04 07:01:02',null,null);

Mysql

2022-05-23

1 269

题解 | #21年8月份练题总数#

select count(distinct device_id) as did_cnt,count(question_id) as question_cnt from question_practice_detail where month(date)=8&&year(date)=2...

Mysql

2022-05-23

1 243

题解 | #截取出年龄#

select substring_index(substring_index(profile,',',-2),',',1) as age,count(device_id) as number from user_submit group by age; //详细看substri...

Mysql

2022-05-23

1 290

题解 | #统计每种性别的人数#

select case when profile like '%,male' then 'male' when profile like '%,female' then 'female' end gender ,count(device_id) from user_submit gr...

Mysql

2022-05-23

0 206

题解 | #查看不同年龄段的用户明细#

select day(date) as day ,count(device_id) as question_cnt from question_practice_detail where year(date)=2021&&month(date)=8 group by date;

Mysql

2022-05-23

1 206

题解 | #查看不同年龄段的用户明细#

select device_id,gender,'20-24岁' from user_profile where age>=20&&age<=24 union select device_id,gender,'25岁及以上' from user_profile...

Mysql

2022-05-23

1 242