- Daily reflection [[Daily reflections]]
  collapsed:: true
	- What I've done
	- What I've thought #thoughts
		- 10:08
			- logseq 比 obsidian 好用，计笔记成本低，而且好用，便携。
	- Mood
		- 10:09
			- 平静且开心(lol)
-
- DONE [#C] 票在书包里
  SCHEDULED: <2023-03-30 Thu>
-
- Todos:
	- Personal
		- DONE 重新浸洗袜子和内裤
		  SCHEDULED: <2023-03-28 Tue 13:00>
		  :LOGBOOK:
		  CLOCK: [2023-03-28 Tue 15:55:30]--[2023-03-28 Tue 15:55:31] => 00:00:01
		  :END:
		- DONE 洗眼镜
		  SCHEDULED: <2023-03-28 Tue 13:00>
		  :LOGBOOK:
		  CLOCK: [2023-03-28 Tue 18:07:51]--[2023-03-28 Tue 22:41:19] => 04:33:28
		  :END:
		- DONE Anki card for cloud collection 还不如没事多翻下书
		  SCHEDULED: <2023-04-01 Sat>
	- School
		- DONE 交选题
		  :LOGBOOK:
		  CLOCK: [2023-03-28 Tue 16:19:35]
		  CLOCK: [2023-03-28 Tue 16:19:40]--[2023-03-28 Tue 18:51:31] => 02:31:51
		  :END:
		- DONE [#A] 复习 java
		  :LOGBOOK:
		  CLOCK: [2023-03-28 Tue 20:03:20]--[2023-03-29 Wed 22:25:48] => 26:22:28
		  :END:
			- DONE 做题
			  :LOGBOOK:
			  CLOCK: [2023-03-28 Tue 20:03:29]--[2023-03-29 Wed 11:11:16] => 15:07:47
			  :END:
				- DONE 练习题
				  :LOGBOOK:
				  CLOCK: [2023-03-28 Tue 20:03:51]--[2023-03-28 Tue 20:39:32] => 00:35:41
				  :END:
				- DONE 往年题
				  :LOGBOOK:
				  CLOCK: [2023-03-28 Tue 20:03:50]--[2023-03-28 Tue 22:41:14] => 02:37:24
				  :END:
				- DONE Leetcode
				  :LOGBOOK:
				  CLOCK: [2023-03-29 Wed 11:19:02]
				  CLOCK: [2023-03-29 Wed 11:19:04]--[2023-03-29 Wed 16:52:09] => 05:33:05
				  :END:
			- DONE 看 ppt
			  :LOGBOOK:
			  CLOCK: [2023-03-28 Tue 20:03:30]--[2023-03-29 Wed 11:18:53] => 15:15:23
			  :END:
-
- OJ problem notes
	- Name:
		- Contains Duplicate
	- Times:
		- Completion time: 14:31
		- Revisions:
	- Tags:
		- Data structures: #hash_table
		- Difficulty: #difficulty_easy
		- Platforms: #leetcode
	- Links:
		- [link to the problem](https://leetcode.com/problems/contains-duplicate/description/)
	- Problem:
		- Given an integer array `nums`, return `true` if any value appears **at least twice** in the array, and return `false` if every element is distinct.
	- Examples:
		- ```
		  
		  
		  Example 1:
		  
		  Input: nums = [1,2,3,1]
		  Output: true
		  
		  Example 2:
		  
		  Input: nums = [1,2,3,4]
		  Output: false
		  
		  Example 3:
		  
		  Input: nums = [1,1,1,3,3,4,3,2,4,2]
		  Output: true
		  
		  ```
	- Constraints:
		- `1 <= nums.length <= 105`
		- `-109 <= nums[i] <= 109`
	- Thoughts:
		- Very simple hash map problem
	- Solution:
		- ```java
		  class Solution {
		      public boolean containsDuplicate(int[] nums) {
		          Set <Integer> set = new HashSet<Integer>();
		          for (int i : nums) {
		              if (set.contains(i)) {
		                  return true;
		              } else {
		                  set.add(i);
		              }
		          }
		  
		          return false;
		      }
		  }
		  ```
	-
	-
-
- Java 练习题 1 #to_be_deleted
  collapsed:: true
	- Q1
		- `less than 10`
	- Q2
		- `greater than 10`
	- Q3
		- `yes`
	- Q4
		- ```
		  zero
		  one
		  none
		  ```
	- Q5
		- ```
		  zero
		  one
		  none
		  one
		  none
		  none
		  ```
	- Q6
		- ```
		  zero
		  none
		  one
		  zero
		  none
		  none
		  ```
	- Q7
		- ```java
		  int sum;
		  for (int i = 1; i <= 100; i++) {
		    sum += i;
		  }
		  System.out.println(sum);
		  ```
	- Q8
		- ```java
		  for (int i = 1; i <= 3; i++) {
		    for (int j = 1; j <= 3; j++) {
		      System.out.print(i * j + " ");
		    }
		    System.out.println();
		  }
		  ```
	- Q9
		- ```
		  9
		  8
		  true
		  ```
	- Q10
		- ```java
		  int sum = 0;
		  for (int i = 1; i <= 99; i++) {
		    if (i % 3 == 0) {
		      sum += i;
		    }
		  }
		  System.out.println(sum);
		  ```
	- Q11 不想写
	- Q12
		- What does overloading mean?
		- What does overloading do?
-
- java 练习题 2 [qmplus](https://qmplus.qmul.ac.uk/course/view.php?id=21582#section-8) #to_be_deleted
	- Q1
		- no.1 : not a array
		  no.2 : `int[] marks = new int[60]`
		  no.3 : `{'a', 'b', 'c'}`
		  no.4 : use ""
	- Q2
		- Compile error
	- Q3
		- `F[1]` is not initiated, it only has a null value
	- Q4
		- Array index out of bounds, f[2] is non-exist
	- Q5
		- compile error, local variable won't be initialized as default val
	- Q6
		- 36, 36.0
	- Q7
		- first one invalid
			- Reason: wrong parameters
		- third one invalid
			- Reason: double->int can't be done implicitly, you have to use type casts
	- Q8
		- ```
		  vroom
		  truck 1
		  car 2
		  ```
	- Q9
		- ```
		  vroomT
		  truck 1
		  car 1
		  ```
	- Q10
		- 634.5
		- Reason: calculated from left to right, all converted to String
	- Q11
		- F, only have access to package-private data
		- F, no multi-inheritance for classes
		- F, not required
		- F, you can have one
	- Q12
		- b
	- Q13
		- false
		- true
		- true (reference stored in string constant pool)
	- Q14
	  collapsed:: true
		- 懒得写了
	- Q15
	  collapsed:: true
		- 懒得写
	- Q16
		- What is a abstract class?
		- What is `toString` method?
		- What does polymorphism mean?