Design HashSet

Leetcode/Easy/Design HashSet.md

@@ -0,0 +1,104 @@
+# Design HashSet
+
+[题目](https://leetcode.com/problems/design-hashset/description/)
+
+又是简单的快乐。
+
+```c#
+public class MyHashSet {
+    List<int> hashSet;
+    public MyHashSet() {
+        hashSet=new();
+    }
+
+    public void Add(int key) {
+        if(!hashSet.Contains(key))
+            hashSet.Add(key);
+    }
+
+    public void Remove(int key) {
+        if(hashSet.Contains(key))
+            hashSet.Remove(key);
+    }
+
+    public bool Contains(int key) {
+        return hashSet.Contains(key);
+    }
+}
+```
+```
+Runtime
+260 ms
+Beats
+28.95%
+Memory
+66.5 MB
+Beats
+53.29%
+```
+魔法位运算解法。
+```c#
+//https://leetcode.com/problems/design-hashset/solutions/769047/java-solution-using-bit-manipulation/
+public class MyHashSet {
+    int[] num;
+    public MyHashSet() {
+        num = new int[31251];
+    }
+
+	// set the bit if that element is present
+    public void Add(int key) {
+        num[getIdx(key)]|=getMask(key);
+    }
+
+	//unset the bit if a key is not present
+    public void Remove(int key) {
+        num[getIdx(key)] &= (~getMask(key));
+    }
+
+	//check if bit corresponding to the key is set or not
+    public bool Contains(int key) {
+        return (num[getIdx(key)]&getMask(key))!=0;
+    }
+
+	// idx of num[] to which this key belongs
+	// for key = 37, it will give 1
+    private int getIdx(int key)
+    {
+        return (key/32);
+    }
+
+	// get mask representing the bit inside num[idx] that corresponds to given key.
+	// for key = 37, it will give 00000000000000000000000000100000
+    private int getMask(int key)
+    {
+        key%=32;
+        return (1<<key);
+    }
+}
+```
+```
+Runtime
+203 ms
+Beats
+97.37%
+Memory
+62 MB
+Beats
+98.3%
+```
+偷懒继承写法（记下来纯粹是图一乐，肯定是不能这么写的）
+```c#
+//https://leetcode.com/problems/design-hashset/solutions/1621844/the-one-liner-solution-that-you-should-not-give/
+public class MyHashSet:HashSet<int> {
+}
+```
+```
+Runtime
+216 ms
+Beats
+89.47%
+Memory
+66.6 MB
+Beats
+53.29%
+```

Leetcode/Leetcode.md

@@ -36,6 +36,7 @@
 - [Matrix Diagonal Sum](./Easy/Matrix%20Diagonal%20Sum.md).
 - [Kth Largest Element in a Stream](./Easy/Kth%20Largest%20Element%20in%20a%20Stream.md). heap.
 - [Design Parking System](./Easy/Design%20Parking%20System.md).
+- [Design HashSet](./Easy/Design%20HashSet.md)
 
 ## Medium
 - [Sum Root to Leaf Numbers](Medium/Sum%20Root%20to%20Leaf%20Numbers.md).Each root-to-leaf path in the tree represents a number. For example, the root-to-leaf path 1 -> 2 -> 3 represents the number 123. Return the total sum of all root-to-leaf numbers. Test cases are generated so that the answer will fit in a 32-bit integer. 返回全部根节点到子节点路径数字的和。

笔记/Tools/工具脚本.md

@@ -1511,13 +1511,15 @@ new_img.save('changed_pixels_flag.png')
 
 ## [hashcat使用](https://xz.aliyun.com/t/4008)
 
-下载：在[官网](https://hashcat.net/hashcat/)下载hashcat binaries，然后用`7z x`解压文件即可。linux运行`hashcat.bin`,windows运行`hashcat.exe`。
+下载：在[官网](https://hashcat.net/hashcat/)下载hashcat binaries，然后用`7z x`解压文件即可(7zip下载：`sudo apt-get install p7zip-full`)。linux运行`hashcat.bin`,windows运行`hashcat.exe`。
 
 运行时指定hash模式的-m选项可以在[这里](https://hashcat.net/wiki/doku.php?id=example_hashes)找到。例如爆破zip，先用[zip2john](https://hashes.com/en/johntheripper/zip2john)将zip转为hash，然后根据hash格式选择-m的参数。-a是爆破模式。
 - 掩码爆破：`./hashcat.bin -a 3 -m 13600 'hash' mask`
 - 字典爆破：`./hashcat.bin -a 0 -m 13600 'hash' dict`
 
-- 小端下将bytes转为数字：`int.from_bytes(msg, 'little')`。类似地，大端填`'big'`。
-
 ## Extracting GPS Coordinates from metadata
-https://github.com/BYU-CSA/BYUCTF-2023/tree/main/lost
+https://github.com/BYU-CSA/BYUCTF-2023/tree/main/lost
+
+## 其他类型
+
+- 小端下将bytes转为数字：`int.from_bytes(msg, 'little')`。类似地，大端填`'big'`。