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build
This commit is contained in:
parent
000a583f92
commit
683e7ee872
7 changed files with 138 additions and 130 deletions
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@ -1562,9 +1562,9 @@ comments: true
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const Self = @This();
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nums: []T = undefined, // 数组(存储列表元素)
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numsCapacity: usize = 10, // 列表容量
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numSize: usize = 0, // 列表长度(即当前元素数量)
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extendRatio: usize = 2, // 每次列表扩容的倍数
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nums_capacity: usize = 10, // 列表容量
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num_size: usize = 0, // 列表长度(即当前元素数量)
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extend_ratio: usize = 2, // 每次列表扩容的倍数
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mem_arena: ?std.heap.ArenaAllocator = null,
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mem_allocator: std.mem.Allocator = undefined, // 内存分配器
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@ -1574,7 +1574,7 @@ comments: true
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self.mem_arena = std.heap.ArenaAllocator.init(allocator);
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self.mem_allocator = self.mem_arena.?.allocator();
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}
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self.nums = try self.mem_allocator.alloc(T, self.numsCapacity);
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self.nums = try self.mem_allocator.alloc(T, self.nums_capacity);
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std.mem.set(T, self.nums, @as(T, 0));
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}
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@ -1586,12 +1586,12 @@ comments: true
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// 获取列表长度(即当前元素数量)
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pub fn size(self: *Self) usize {
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return self.numSize;
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return self.num_size;
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}
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// 获取列表容量
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pub fn capacity(self: *Self) usize {
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return self.numsCapacity;
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return self.nums_capacity;
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}
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// 访问元素
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@ -1614,7 +1614,7 @@ comments: true
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if (self.size() == self.capacity()) try self.extendCapacity();
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self.nums[self.size()] = num;
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// 更新元素数量
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self.numSize += 1;
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self.num_size += 1;
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}
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// 中间插入元素
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@ -1629,7 +1629,7 @@ comments: true
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}
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self.nums[index] = num;
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// 更新元素数量
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self.numSize += 1;
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self.num_size += 1;
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}
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// 删除元素
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@ -1642,22 +1642,22 @@ comments: true
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self.nums[j] = self.nums[j + 1];
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}
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// 更新元素数量
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self.numSize -= 1;
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self.num_size -= 1;
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// 返回被删除元素
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return num;
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}
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// 列表扩容
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pub fn extendCapacity(self: *Self) !void {
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// 新建一个长度为 size * extendRatio 的数组,并将原数组拷贝到新数组
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var newCapacity = self.capacity() * self.extendRatio;
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// 新建一个长度为 size * extend_ratio 的数组,并将原数组拷贝到新数组
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var newCapacity = self.capacity() * self.extend_ratio;
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var extend = try self.mem_allocator.alloc(T, newCapacity);
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std.mem.set(T, extend, @as(T, 0));
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// 将原数组中的所有元素复制到新数组
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std.mem.copy(T, extend, self.nums);
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self.nums = extend;
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// 更新列表容量
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self.numsCapacity = newCapacity;
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self.nums_capacity = newCapacity;
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}
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// 将列表转换为数组
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@ -952,7 +952,9 @@ comments: true
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/* 打印邻接表 */
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void print() {
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cout << "邻接表 =" << endl;
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for (auto& [key, vec] : adjList) {
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for (auto& adj : adjList) {
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const auto& key= adj.first;
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const auto& vec = adj.second;
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cout << key->val << ": ";
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PrintUtil::printVector(vetsToVals(vec));
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}
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@ -6,15 +6,15 @@ comments: true
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理想情况下,哈希函数应该为每个输入产生唯一的输出,使得 key 和 value 一一对应。而实际上,往往存在向哈希函数输入不同的 key 而产生相同输出的情况,这种情况被称为「哈希冲突 Hash Collision」。哈希冲突会导致查询结果错误,从而严重影响哈希表的可用性。
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那么,为什么会出现哈希冲突呢?本质上看,**由于哈希函数的输入空间往往远大于输出空间**,因此不可避免地会出现多个输入产生相同输出的情况,即为哈希冲突。比如,输入空间是全体整数,输出空间是一个固定大小的桶(数组)的索引范围,那么必定会有多个整数同时映射到一个桶索引。
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那么,为什么会出现哈希冲突呢?本质上看,**由于哈希函数的输入空间往往远大于输出空间**,因此不可避免地会出现多个输入产生相同输出的情况,即为哈希冲突。比如,输入空间是全体整数,输出空间是一个固定大小的数组,那么必定会有多个整数映射到同一个数组索引。
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为了缓解哈希冲突,一方面,**我们可以通过哈希表扩容来减小冲突概率**。极端情况下,当输入空间和输出空间大小相等时,哈希表就等价于数组了,可谓“大力出奇迹”。
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为了缓解哈希冲突,一方面,**我们可以通过哈希表扩容来减小冲突概率**。极端情况下,当输入空间和输出空间大小相等时,哈希表就等价于数组了,每个 key 都对应唯一的数组索引,可谓“大力出奇迹”。
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另一方面,**考虑通过优化哈希表的表示方式以缓解哈希冲突**,常见的方法有「链式地址」和「开放寻址」。
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另一方面,**考虑通过优化哈希表的来缓解哈希冲突**,常见的方法有「链式地址」和「开放寻址」。
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## 6.2.1. 哈希表扩容
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「负载因子 Load Factor」定义为 **哈希表中元素数量除以桶槽数量(即数组大小)**,代表哈希冲突的严重程度。
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「负载因子 Load Factor」定义为 **哈希表中元素数量除以桶数量(即数组大小)**,代表哈希冲突的严重程度。
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**负载因子常用作哈希表扩容的触发条件**。比如在 Java 中,当负载因子 $> 0.75$ 时则触发扩容,将 HashMap 大小扩充至原先的 $2$ 倍。
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@ -22,7 +22,7 @@ comments: true
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## 6.2.2. 链式地址
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在原始哈希表中,桶内的每个地址只能存储一个元素(即键值对)。**考虑将单个元素转化成一个链表,将所有冲突元素都存储在一个链表中**。
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在原始哈希表中,每个桶只能存储一个元素(即键值对)。**考虑将单个元素转化成一个链表,将所有冲突元素都存储在一个链表中**。
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![链式地址](hash_collision.assets/hash_collision_chaining.png)
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链式地址下,哈希表操作方法为:
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- **查询元素**:先将 key 输入到哈希函数得到桶内索引,即可访问链表头结点,再通过遍历链表查找对应 value 。
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- **查询元素**:输入 key ,经过哈希函数得到数组索引,即可访问链表头结点,再通过遍历链表并对比 key 来查找键值对。
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- **添加元素**:先通过哈希函数访问链表头部,再将结点(即键值对)添加到链表头部即可。
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- **删除元素**:同样先根据哈希函数结果访问链表头部,再遍历链表查找对应结点,删除之即可。
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@ -62,8 +62,8 @@ comments: true
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线性探测存在以下缺陷:
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- **不能直接删除元素**。删除元素会导致桶内出现一个空位,在查找其他元素时,该空位有可能导致程序认为元素不存在(即上述第 `2.` 种情况)。因此需要借助一个标志位来标记删除元素。
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- **容易产生聚集**。桶内被占用的连续位置越长,这些连续位置发生哈希冲突的可能性越大,从而进一步促进这一位置的“聚堆生长”,最终导致增删查改操作效率的劣化。
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- **不能直接删除元素**。删除元素会导致数组内出现一个空位,在查找其他元素时,该空位有可能导致程序认为元素不存在(即上述第 `2.` 种情况)。因此需要借助一个标志位来标记删除元素。
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- **容易产生聚集**。数组内被占用的连续位置越长,这些连续位置发生哈希冲突的可能性越大,从而进一步促进这一位置的“聚堆生长”,最终导致增删查改操作效率的劣化。
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### 多次哈希
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Java 采用「链式地址」。在 JDK 1.8 之后,HashMap 内数组长度大于 64 时,长度大于 8 的链表会被转化为「红黑树」,以提升查找性能。
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Python 采用「开放寻址」。字典 dict 使用伪随机数进行探测。
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Golang 采用「链式地址」。Go 规定每个桶最多存储 8 个键值对,超出容量则连接一个溢出桶;当溢出桶过多时,会执行一次特殊的等量扩容操作,以保证性能。
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@ -396,14 +396,16 @@ comments: true
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## 6.1.3. 哈希函数
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哈希表中存储元素的数据结构被称为「桶 Bucket」,底层实现可能是数组、链表、二叉树(红黑树),或是它们的组合。
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哈希表的底层实现是数组,并且可能包含链表、二叉树(红黑树)等数据结构,以提升查询性能(下节会讨论)。
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最简单地,**我们可以仅用一个「数组」来实现哈希表**。首先,将所有 value 放入数组中,那么每个 value 在数组中都有唯一的「索引」。显然,访问 value 需要给定索引,而为了 **建立 key 和索引之间的映射关系**,我们需要使用「哈希函数 Hash Function」。
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首先考虑最简单的情况,**即仅用一个「数组」来实现哈希表**。根据习惯,我们将数组中的每个空位称为「桶 Bucket」,用于存储键值对。
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设数组为 `bucket` ,哈希函数为 `f(x)` ,输入键为 `key` 。那么获取 value 的步骤为:
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我们将键值对 key, value 包装成一个类 `Entry` ,并将所有 `Entry` 都放入数组中,那么每个 `Entry` 在数组中都有唯一的索引。显然,访问 `Entry` 需要给定索引,而为了 **建立 key 和索引之间的映射关系**,我们需要使用「哈希函数 Hash Function」。
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具体地,设数组为 `buckets` ,哈希函数为 `f(x)` ,输入键为 `key` 。那么获取 value 的步骤为:
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1. 通过哈希函数计算出索引,即 `index = f(key)` ;
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2. 通过索引在数组中获取值,即 `value = bucket[index]` ;
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2. 通过索引在数组中获取键值对,即 `Entry = buckets[index]` ;
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以上述学生数据 `key 学号 -> value 姓名` 为例,我们可以将「哈希函数」设计为
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@ -411,6 +413,8 @@ $$
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f(x) = x \% 100
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$$
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如下图所示,输入一个学号 key ,经过哈希函数计算就能访问到对应的姓名 value 。
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![简单哈希函数示例](hash_map.assets/hash_function.png)
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<p align="center"> Fig. 简单哈希函数示例 </p>
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@ -430,12 +434,12 @@ $$
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/* 基于数组简易实现的哈希表 */
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class ArrayHashMap {
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private List<Entry> bucket;
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private List<Entry> buckets;
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public ArrayHashMap() {
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// 初始化一个长度为 100 的桶(数组)
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bucket = new ArrayList<>();
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buckets = new ArrayList<>();
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for (int i = 0; i < 100; i++) {
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bucket.add(null);
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buckets.add(null);
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}
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}
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@ -448,7 +452,7 @@ $$
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/* 查询操作 */
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public String get(int key) {
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int index = hashFunc(key);
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Entry pair = bucket.get(index);
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Entry pair = buckets.get(index);
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if (pair == null) return null;
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return pair.val;
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}
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@ -457,20 +461,20 @@ $$
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public void put(int key, String val) {
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Entry pair = new Entry(key, val);
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int index = hashFunc(key);
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bucket.set(index, pair);
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buckets.set(index, pair);
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}
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/* 删除操作 */
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public void remove(int key) {
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int index = hashFunc(key);
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// 置为 null ,代表删除
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bucket.set(index, null);
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buckets.set(index, null);
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}
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/* 获取所有键值对 */
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public List<Entry> entrySet() {
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List<Entry> entrySet = new ArrayList<>();
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for (Entry pair : bucket) {
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for (Entry pair : buckets) {
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if (pair != null)
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entrySet.add(pair);
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}
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/* 获取所有键 */
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public List<Integer> keySet() {
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List<Integer> keySet = new ArrayList<>();
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for (Entry pair : bucket) {
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for (Entry pair : buckets) {
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if (pair != null)
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keySet.add(pair.key);
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}
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@ -490,7 +494,7 @@ $$
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/* 获取所有值 */
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public List<String> valueSet() {
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List<String> valueSet = new ArrayList<>();
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for (Entry pair : bucket) {
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for (Entry pair : buckets) {
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if (pair != null)
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valueSet.add(pair.val);
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}
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/* 基于数组简易实现的哈希表 */
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class ArrayHashMap {
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private:
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vector<Entry*> bucket;
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vector<Entry*> buckets;
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public:
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ArrayHashMap() {
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// 初始化一个长度为 100 的桶(数组)
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bucket= vector<Entry*>(100);
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buckets= vector<Entry*>(100);
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}
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/* 哈希函数 */
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@ -539,7 +543,7 @@ $$
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/* 查询操作 */
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string get(int key) {
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int index = hashFunc(key);
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Entry* pair = bucket[index];
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Entry* pair = buckets[index];
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if (pair == nullptr)
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return nullptr;
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return pair->val;
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@ -549,20 +553,20 @@ $$
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void put(int key, string val) {
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Entry* pair = new Entry(key, val);
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int index = hashFunc(key);
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bucket[index] = pair;
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buckets[index] = pair;
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}
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/* 删除操作 */
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void remove(int key) {
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int index = hashFunc(key);
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// 置为 nullptr ,代表删除
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bucket[index] = nullptr;
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buckets[index] = nullptr;
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}
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/* 获取所有键值对 */
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vector<Entry*> entrySet() {
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vector<Entry*> entrySet;
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for (Entry* pair: bucket) {
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for (Entry* pair: buckets) {
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if (pair != nullptr) {
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entrySet.push_back(pair);
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}
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/* 获取所有键 */
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vector<int> keySet() {
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vector<int> keySet;
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for (Entry* pair: bucket) {
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for (Entry* pair: buckets) {
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if (pair != nullptr) {
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keySet.push_back(pair->key);
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}
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/* 获取所有值 */
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vector<string> valueSet() {
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vector<string> valueSet;
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for (Entry* pair: bucket) {
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for (Entry* pair: buckets) {
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if (pair != nullptr){
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valueSet.push_back(pair->val);
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}
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def __init__(self):
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""" 构造方法 """
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# 初始化一个长度为 100 的桶(数组)
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self.bucket: List[Optional[Entry]] = [None] * 100
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self.buckets: List[Optional[Entry]] = [None] * 100
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def hash_func(self, key: int) -> int:
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""" 哈希函数 """
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@ -625,7 +629,7 @@ $$
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def get(self, key: int) -> str:
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""" 查询操作 """
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index: int = self.hash_func(key)
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pair: Entry = self.bucket[index]
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pair: Entry = self.buckets[index]
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if pair is None:
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return None
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return pair.val
|
||||
|
@ -634,18 +638,18 @@ $$
|
|||
""" 添加操作 """
|
||||
pair = Entry(key, val)
|
||||
index: int = self.hash_func(key)
|
||||
self.bucket[index] = pair
|
||||
self.buckets[index] = pair
|
||||
|
||||
def remove(self, key: int) -> None:
|
||||
""" 删除操作 """
|
||||
index: int = self.hash_func(key)
|
||||
# 置为 None ,代表删除
|
||||
self.bucket[index] = None
|
||||
self.buckets[index] = None
|
||||
|
||||
def entry_set(self) -> List[Entry]:
|
||||
""" 获取所有键值对 """
|
||||
result: List[Entry] = []
|
||||
for pair in self.bucket:
|
||||
for pair in self.buckets:
|
||||
if pair is not None:
|
||||
result.append(pair)
|
||||
return result
|
||||
|
@ -653,7 +657,7 @@ $$
|
|||
def key_set(self) -> List[int]:
|
||||
""" 获取所有键 """
|
||||
result: List[int] = []
|
||||
for pair in self.bucket:
|
||||
for pair in self.buckets:
|
||||
if pair is not None:
|
||||
result.append(pair.key)
|
||||
return result
|
||||
|
@ -661,14 +665,14 @@ $$
|
|||
def value_set(self) -> List[str]:
|
||||
""" 获取所有值 """
|
||||
result: List[str] = []
|
||||
for pair in self.bucket:
|
||||
for pair in self.buckets:
|
||||
if pair is not None:
|
||||
result.append(pair.val)
|
||||
return result
|
||||
|
||||
def print(self) -> None:
|
||||
""" 打印哈希表 """
|
||||
for pair in self.bucket:
|
||||
for pair in self.buckets:
|
||||
if pair is not None:
|
||||
print(pair.key, "->", pair.val)
|
||||
```
|
||||
|
@ -684,14 +688,14 @@ $$
|
|||
|
||||
/* 基于数组简易实现的哈希表 */
|
||||
type arrayHashMap struct {
|
||||
bucket []*entry
|
||||
buckets []*entry
|
||||
}
|
||||
|
||||
/* 初始化哈希表 */
|
||||
func newArrayHashMap() *arrayHashMap {
|
||||
// 初始化一个长度为 100 的桶(数组)
|
||||
bucket := make([]*entry, 100)
|
||||
return &arrayHashMap{bucket: bucket}
|
||||
buckets := make([]*entry, 100)
|
||||
return &arrayHashMap{buckets: buckets}
|
||||
}
|
||||
|
||||
/* 哈希函数 */
|
||||
|
@ -703,7 +707,7 @@ $$
|
|||
/* 查询操作 */
|
||||
func (a *arrayHashMap) get(key int) string {
|
||||
index := a.hashFunc(key)
|
||||
pair := a.bucket[index]
|
||||
pair := a.buckets[index]
|
||||
if pair == nil {
|
||||
return "Not Found"
|
||||
}
|
||||
|
@ -714,20 +718,20 @@ $$
|
|||
func (a *arrayHashMap) put(key int, val string) {
|
||||
pair := &entry{key: key, val: val}
|
||||
index := a.hashFunc(key)
|
||||
a.bucket[index] = pair
|
||||
a.buckets[index] = pair
|
||||
}
|
||||
|
||||
/* 删除操作 */
|
||||
func (a *arrayHashMap) remove(key int) {
|
||||
index := a.hashFunc(key)
|
||||
// 置为 nil ,代表删除
|
||||
a.bucket[index] = nil
|
||||
a.buckets[index] = nil
|
||||
}
|
||||
|
||||
/* 获取所有键对 */
|
||||
func (a *arrayHashMap) entrySet() []*entry {
|
||||
var pairs []*entry
|
||||
for _, pair := range a.bucket {
|
||||
for _, pair := range a.buckets {
|
||||
if pair != nil {
|
||||
pairs = append(pairs, pair)
|
||||
}
|
||||
|
@ -738,7 +742,7 @@ $$
|
|||
/* 获取所有键 */
|
||||
func (a *arrayHashMap) keySet() []int {
|
||||
var keys []int
|
||||
for _, pair := range a.bucket {
|
||||
for _, pair := range a.buckets {
|
||||
if pair != nil {
|
||||
keys = append(keys, pair.key)
|
||||
}
|
||||
|
@ -749,7 +753,7 @@ $$
|
|||
/* 获取所有值 */
|
||||
func (a *arrayHashMap) valueSet() []string {
|
||||
var values []string
|
||||
for _, pair := range a.bucket {
|
||||
for _, pair := range a.buckets {
|
||||
if pair != nil {
|
||||
values = append(values, pair.val)
|
||||
}
|
||||
|
@ -759,7 +763,7 @@ $$
|
|||
|
||||
/* 打印哈希表 */
|
||||
func (a *arrayHashMap) print() {
|
||||
for _, pair := range a.bucket {
|
||||
for _, pair := range a.buckets {
|
||||
if pair != nil {
|
||||
fmt.Println(pair.key, "->", pair.val)
|
||||
}
|
||||
|
@ -780,10 +784,10 @@ $$
|
|||
|
||||
/* 基于数组简易实现的哈希表 */
|
||||
class ArrayHashMap {
|
||||
#bucket;
|
||||
#buckets;
|
||||
constructor() {
|
||||
// 初始化一个长度为 100 的桶(数组)
|
||||
this.#bucket = new Array(100).fill(null);
|
||||
this.#buckets = new Array(100).fill(null);
|
||||
}
|
||||
|
||||
/* 哈希函数 */
|
||||
|
@ -794,7 +798,7 @@ $$
|
|||
/* 查询操作 */
|
||||
get(key) {
|
||||
let index = this.#hashFunc(key);
|
||||
let entry = this.#bucket[index];
|
||||
let entry = this.#buckets[index];
|
||||
if (entry === null) return null;
|
||||
return entry.val;
|
||||
}
|
||||
|
@ -802,22 +806,22 @@ $$
|
|||
/* 添加操作 */
|
||||
set(key, val) {
|
||||
let index = this.#hashFunc(key);
|
||||
this.#bucket[index] = new Entry(key, val);
|
||||
this.#buckets[index] = new Entry(key, val);
|
||||
}
|
||||
|
||||
/* 删除操作 */
|
||||
delete(key) {
|
||||
let index = this.#hashFunc(key);
|
||||
// 置为 null ,代表删除
|
||||
this.#bucket[index] = null;
|
||||
this.#buckets[index] = null;
|
||||
}
|
||||
|
||||
/* 获取所有键值对 */
|
||||
entries() {
|
||||
let arr = [];
|
||||
for (let i = 0; i < this.#bucket.length; i++) {
|
||||
if (this.#bucket[i]) {
|
||||
arr.push(this.#bucket[i]);
|
||||
for (let i = 0; i < this.#buckets.length; i++) {
|
||||
if (this.#buckets[i]) {
|
||||
arr.push(this.#buckets[i]);
|
||||
}
|
||||
}
|
||||
return arr;
|
||||
|
@ -826,9 +830,9 @@ $$
|
|||
/* 获取所有键 */
|
||||
keys() {
|
||||
let arr = [];
|
||||
for (let i = 0; i < this.#bucket.length; i++) {
|
||||
if (this.#bucket[i]) {
|
||||
arr.push(this.#bucket[i]?.key);
|
||||
for (let i = 0; i < this.#buckets.length; i++) {
|
||||
if (this.#buckets[i]) {
|
||||
arr.push(this.#buckets[i]?.key);
|
||||
}
|
||||
}
|
||||
return arr;
|
||||
|
@ -837,9 +841,9 @@ $$
|
|||
/* 获取所有值 */
|
||||
values() {
|
||||
let arr = [];
|
||||
for (let i = 0; i < this.#bucket.length; i++) {
|
||||
if (this.#bucket[i]) {
|
||||
arr.push(this.#bucket[i]?.val);
|
||||
for (let i = 0; i < this.#buckets.length; i++) {
|
||||
if (this.#buckets[i]) {
|
||||
arr.push(this.#buckets[i]?.val);
|
||||
}
|
||||
}
|
||||
return arr;
|
||||
|
@ -873,11 +877,11 @@ $$
|
|||
/* 基于数组简易实现的哈希表 */
|
||||
class ArrayHashMap {
|
||||
|
||||
private readonly bucket: (Entry | null)[];
|
||||
private readonly buckets: (Entry | null)[];
|
||||
|
||||
constructor() {
|
||||
// 初始化一个长度为 100 的桶(数组)
|
||||
this.bucket = (new Array(100)).fill(null);
|
||||
this.buckets = (new Array(100)).fill(null);
|
||||
}
|
||||
|
||||
/* 哈希函数 */
|
||||
|
@ -888,7 +892,7 @@ $$
|
|||
/* 查询操作 */
|
||||
public get(key: number): string | null {
|
||||
let index = this.hashFunc(key);
|
||||
let entry = this.bucket[index];
|
||||
let entry = this.buckets[index];
|
||||
if (entry === null) return null;
|
||||
return entry.val;
|
||||
}
|
||||
|
@ -896,22 +900,22 @@ $$
|
|||
/* 添加操作 */
|
||||
public set(key: number, val: string) {
|
||||
let index = this.hashFunc(key);
|
||||
this.bucket[index] = new Entry(key, val);
|
||||
this.buckets[index] = new Entry(key, val);
|
||||
}
|
||||
|
||||
/* 删除操作 */
|
||||
public delete(key: number) {
|
||||
let index = this.hashFunc(key);
|
||||
// 置为 null ,代表删除
|
||||
this.bucket[index] = null;
|
||||
this.buckets[index] = null;
|
||||
}
|
||||
|
||||
/* 获取所有键值对 */
|
||||
public entries(): (Entry | null)[] {
|
||||
let arr: (Entry | null)[] = [];
|
||||
for (let i = 0; i < this.bucket.length; i++) {
|
||||
if (this.bucket[i]) {
|
||||
arr.push(this.bucket[i]);
|
||||
for (let i = 0; i < this.buckets.length; i++) {
|
||||
if (this.buckets[i]) {
|
||||
arr.push(this.buckets[i]);
|
||||
}
|
||||
}
|
||||
return arr;
|
||||
|
@ -920,9 +924,9 @@ $$
|
|||
/* 获取所有键 */
|
||||
public keys(): (number | undefined)[] {
|
||||
let arr: (number | undefined)[] = [];
|
||||
for (let i = 0; i < this.bucket.length; i++) {
|
||||
if (this.bucket[i]) {
|
||||
arr.push(this.bucket[i]?.key);
|
||||
for (let i = 0; i < this.buckets.length; i++) {
|
||||
if (this.buckets[i]) {
|
||||
arr.push(this.buckets[i]?.key);
|
||||
}
|
||||
}
|
||||
return arr;
|
||||
|
@ -931,9 +935,9 @@ $$
|
|||
/* 获取所有值 */
|
||||
public values(): (string | undefined)[] {
|
||||
let arr: (string | undefined)[] = [];
|
||||
for (let i = 0; i < this.bucket.length; i++) {
|
||||
if (this.bucket[i]) {
|
||||
arr.push(this.bucket[i]?.val);
|
||||
for (let i = 0; i < this.buckets.length; i++) {
|
||||
if (this.buckets[i]) {
|
||||
arr.push(this.buckets[i]?.val);
|
||||
}
|
||||
}
|
||||
return arr;
|
||||
|
@ -976,14 +980,14 @@ $$
|
|||
/* 基于数组简易实现的哈希表 */
|
||||
class ArrayHashMap
|
||||
{
|
||||
private List<Entry?> bucket;
|
||||
private List<Entry?> buckets;
|
||||
public ArrayHashMap()
|
||||
{
|
||||
// 初始化一个长度为 100 的桶(数组)
|
||||
bucket = new();
|
||||
buckets = new();
|
||||
for (int i = 0; i < 100; i++)
|
||||
{
|
||||
bucket.Add(null);
|
||||
buckets.Add(null);
|
||||
}
|
||||
}
|
||||
|
||||
|
@ -998,7 +1002,7 @@ $$
|
|||
public String? get(int key)
|
||||
{
|
||||
int index = hashFunc(key);
|
||||
Entry? pair = bucket[index];
|
||||
Entry? pair = buckets[index];
|
||||
if (pair == null) return null;
|
||||
return pair.val;
|
||||
}
|
||||
|
@ -1008,7 +1012,7 @@ $$
|
|||
{
|
||||
Entry pair = new Entry(key, val);
|
||||
int index = hashFunc(key);
|
||||
bucket[index] = pair;
|
||||
buckets[index] = pair;
|
||||
}
|
||||
|
||||
/* 删除操作 */
|
||||
|
@ -1016,14 +1020,14 @@ $$
|
|||
{
|
||||
int index = hashFunc(key);
|
||||
// 置为 null ,代表删除
|
||||
bucket[index] = null;
|
||||
buckets[index] = null;
|
||||
}
|
||||
|
||||
/* 获取所有键值对 */
|
||||
public List<Entry> entrySet()
|
||||
{
|
||||
List<Entry> entrySet = new();
|
||||
foreach (Entry? pair in bucket)
|
||||
foreach (Entry? pair in buckets)
|
||||
{
|
||||
if (pair != null)
|
||||
entrySet.Add(pair);
|
||||
|
@ -1035,7 +1039,7 @@ $$
|
|||
public List<int> keySet()
|
||||
{
|
||||
List<int> keySet = new();
|
||||
foreach (Entry? pair in bucket)
|
||||
foreach (Entry? pair in buckets)
|
||||
{
|
||||
if (pair != null)
|
||||
keySet.Add(pair.key);
|
||||
|
@ -1047,7 +1051,7 @@ $$
|
|||
public List<String> valueSet()
|
||||
{
|
||||
List<String> valueSet = new();
|
||||
foreach (Entry? pair in bucket)
|
||||
foreach (Entry? pair in buckets)
|
||||
{
|
||||
if (pair != null)
|
||||
valueSet.Add(pair.val);
|
||||
|
@ -1082,12 +1086,12 @@ $$
|
|||
|
||||
/* 基于数组简易实现的哈希表 */
|
||||
class ArrayHashMap {
|
||||
private var bucket: [Entry?] = []
|
||||
private var buckets: [Entry?] = []
|
||||
|
||||
init() {
|
||||
// 初始化一个长度为 100 的桶(数组)
|
||||
for _ in 0 ..< 100 {
|
||||
bucket.append(nil)
|
||||
buckets.append(nil)
|
||||
}
|
||||
}
|
||||
|
||||
|
@ -1100,7 +1104,7 @@ $$
|
|||
/* 查询操作 */
|
||||
func get(key: Int) -> String? {
|
||||
let index = hashFunc(key: key)
|
||||
let pair = bucket[index]
|
||||
let pair = buckets[index]
|
||||
return pair?.val
|
||||
}
|
||||
|
||||
|
@ -1108,20 +1112,20 @@ $$
|
|||
func put(key: Int, val: String) {
|
||||
let pair = Entry(key: key, val: val)
|
||||
let index = hashFunc(key: key)
|
||||
bucket[index] = pair
|
||||
buckets[index] = pair
|
||||
}
|
||||
|
||||
/* 删除操作 */
|
||||
func remove(key: Int) {
|
||||
let index = hashFunc(key: key)
|
||||
// 置为 nil ,代表删除
|
||||
bucket[index] = nil
|
||||
buckets[index] = nil
|
||||
}
|
||||
|
||||
/* 获取所有键值对 */
|
||||
func entrySet() -> [Entry] {
|
||||
var entrySet: [Entry] = []
|
||||
for pair in bucket {
|
||||
for pair in buckets {
|
||||
if let pair = pair {
|
||||
entrySet.append(pair)
|
||||
}
|
||||
|
@ -1132,7 +1136,7 @@ $$
|
|||
/* 获取所有键 */
|
||||
func keySet() -> [Int] {
|
||||
var keySet: [Int] = []
|
||||
for pair in bucket {
|
||||
for pair in buckets {
|
||||
if let pair = pair {
|
||||
keySet.append(pair.key)
|
||||
}
|
||||
|
@ -1143,7 +1147,7 @@ $$
|
|||
/* 获取所有值 */
|
||||
func valueSet() -> [String] {
|
||||
var valueSet: [String] = []
|
||||
for pair in bucket {
|
||||
for pair in buckets {
|
||||
if let pair = pair {
|
||||
valueSet.append(pair.val)
|
||||
}
|
||||
|
@ -1179,7 +1183,7 @@ $$
|
|||
// 基于数组简易实现的哈希表
|
||||
fn ArrayHashMap(comptime T: type) type {
|
||||
return struct {
|
||||
bucket: ?std.ArrayList(?T) = null,
|
||||
buckets: ?std.ArrayList(?T) = null,
|
||||
mem_allocator: std.mem.Allocator = undefined,
|
||||
|
||||
const Self = @This();
|
||||
|
@ -1188,16 +1192,16 @@ $$
|
|||
pub fn init(self: *Self, allocator: std.mem.Allocator) !void {
|
||||
self.mem_allocator = allocator;
|
||||
// 初始化一个长度为 100 的桶(数组)
|
||||
self.bucket = std.ArrayList(?T).init(self.mem_allocator);
|
||||
self.buckets = std.ArrayList(?T).init(self.mem_allocator);
|
||||
var i: i32 = 0;
|
||||
while (i < 100) : (i += 1) {
|
||||
try self.bucket.?.append(null);
|
||||
try self.buckets.?.append(null);
|
||||
}
|
||||
}
|
||||
|
||||
// 析构方法
|
||||
pub fn deinit(self: *Self) void {
|
||||
if (self.bucket != null) self.bucket.?.deinit();
|
||||
if (self.buckets != null) self.buckets.?.deinit();
|
||||
}
|
||||
|
||||
// 哈希函数
|
||||
|
@ -1209,7 +1213,7 @@ $$
|
|||
// 查询操作
|
||||
pub fn get(self: *Self, key: usize) []const u8 {
|
||||
var index = hashFunc(key);
|
||||
var pair = self.bucket.?.items[index];
|
||||
var pair = self.buckets.?.items[index];
|
||||
return pair.?.val;
|
||||
}
|
||||
|
||||
|
@ -1217,20 +1221,20 @@ $$
|
|||
pub fn put(self: *Self, key: usize, val: []const u8) !void {
|
||||
var pair = Entry.init(key, val);
|
||||
var index = hashFunc(key);
|
||||
self.bucket.?.items[index] = pair;
|
||||
self.buckets.?.items[index] = pair;
|
||||
}
|
||||
|
||||
// 删除操作
|
||||
pub fn remove(self: *Self, key: usize) !void {
|
||||
var index = hashFunc(key);
|
||||
// 置为 null ,代表删除
|
||||
self.bucket.?.items[index] = null;
|
||||
self.buckets.?.items[index] = null;
|
||||
}
|
||||
|
||||
// 获取所有键值对
|
||||
pub fn entrySet(self: *Self) !*std.ArrayList(T) {
|
||||
var entry_set = std.ArrayList(T).init(self.mem_allocator);
|
||||
for (self.bucket.?.items) |item| {
|
||||
for (self.buckets.?.items) |item| {
|
||||
if (item == null) continue;
|
||||
try entry_set.append(item.?);
|
||||
}
|
||||
|
@ -1240,7 +1244,7 @@ $$
|
|||
// 获取所有键
|
||||
pub fn keySet(self: *Self) !*std.ArrayList(usize) {
|
||||
var key_set = std.ArrayList(usize).init(self.mem_allocator);
|
||||
for (self.bucket.?.items) |item| {
|
||||
for (self.buckets.?.items) |item| {
|
||||
if (item == null) continue;
|
||||
try key_set.append(item.?.key);
|
||||
}
|
||||
|
@ -1250,7 +1254,7 @@ $$
|
|||
// 获取所有值
|
||||
pub fn valueSet(self: *Self) !*std.ArrayList([]const u8) {
|
||||
var value_set = std.ArrayList([]const u8).init(self.mem_allocator);
|
||||
for (self.bucket.?.items) |item| {
|
||||
for (self.buckets.?.items) |item| {
|
||||
if (item == null) continue;
|
||||
try value_set.append(item.?.val);
|
||||
}
|
||||
|
|
|
@ -141,10 +141,10 @@ comments: true
|
|||
```zig title="my_heap.zig"
|
||||
// 构造方法,根据输入列表建堆
|
||||
fn init(self: *Self, allocator: std.mem.Allocator, nums: []const T) !void {
|
||||
if (self.maxHeap != null) return;
|
||||
self.maxHeap = std.ArrayList(T).init(allocator);
|
||||
if (self.max_heap != null) return;
|
||||
self.max_heap = std.ArrayList(T).init(allocator);
|
||||
// 将列表元素原封不动添加进堆
|
||||
try self.maxHeap.?.appendSlice(nums);
|
||||
try self.max_heap.?.appendSlice(nums);
|
||||
// 堆化除叶结点以外的其他所有结点
|
||||
var i: usize = parent(self.size() - 1) + 1;
|
||||
while (i > 0) : (i -= 1) {
|
||||
|
|
|
@ -594,7 +594,7 @@ comments: true
|
|||
```zig title="my_heap.zig"
|
||||
// 访问堆顶元素
|
||||
fn peek(self: *Self) T {
|
||||
return self.maxHeap.?.items[0];
|
||||
return self.max_heap.?.items[0];
|
||||
}
|
||||
```
|
||||
|
||||
|
@ -855,7 +855,7 @@ comments: true
|
|||
// 元素入堆
|
||||
fn push(self: *Self, val: T) !void {
|
||||
// 添加结点
|
||||
try self.maxHeap.?.append(val);
|
||||
try self.max_heap.?.append(val);
|
||||
// 从底至顶堆化
|
||||
try self.siftUp(self.size() - 1);
|
||||
}
|
||||
|
@ -867,7 +867,7 @@ comments: true
|
|||
// 获取结点 i 的父结点
|
||||
var p = parent(i);
|
||||
// 当“越过根结点”或“结点无需修复”时,结束堆化
|
||||
if (p < 0 or self.maxHeap.?.items[i] <= self.maxHeap.?.items[p]) break;
|
||||
if (p < 0 or self.max_heap.?.items[i] <= self.max_heap.?.items[p]) break;
|
||||
// 交换两结点
|
||||
try self.swap(i, p);
|
||||
// 循环向上堆化
|
||||
|
@ -1247,7 +1247,7 @@ comments: true
|
|||
// 交换根结点与最右叶结点(即交换首元素与尾元素)
|
||||
try self.swap(0, self.size() - 1);
|
||||
// 删除结点
|
||||
var val = self.maxHeap.?.pop();
|
||||
var val = self.max_heap.?.pop();
|
||||
// 从顶至底堆化
|
||||
try self.siftDown(0);
|
||||
// 返回堆顶元素
|
||||
|
@ -1262,8 +1262,8 @@ comments: true
|
|||
var l = left(i);
|
||||
var r = right(i);
|
||||
var ma = i;
|
||||
if (l < self.size() and self.maxHeap.?.items[l] > self.maxHeap.?.items[ma]) ma = l;
|
||||
if (r < self.size() and self.maxHeap.?.items[r] > self.maxHeap.?.items[ma]) ma = r;
|
||||
if (l < self.size() and self.max_heap.?.items[l] > self.max_heap.?.items[ma]) ma = l;
|
||||
if (r < self.size() and self.max_heap.?.items[r] > self.max_heap.?.items[ma]) ma = r;
|
||||
// 若结点 i 最大或索引 l, r 越界,则无需继续堆化,跳出
|
||||
if (ma == i) break;
|
||||
// 交换两结点
|
||||
|
|
|
@ -1541,7 +1541,7 @@ comments: true
|
|||
nums: []T = undefined, // 用于存储队列元素的数组
|
||||
cap: usize = 0, // 队列容量
|
||||
front: usize = 0, // 队首指针,指向队首元素
|
||||
queSize: usize = 0, // 尾指针,指向队尾 + 1
|
||||
que_size: usize = 0, // 尾指针,指向队尾 + 1
|
||||
mem_arena: ?std.heap.ArenaAllocator = null,
|
||||
mem_allocator: std.mem.Allocator = undefined, // 内存分配器
|
||||
|
||||
|
@ -1569,12 +1569,12 @@ comments: true
|
|||
|
||||
// 获取队列的长度
|
||||
pub fn size(self: *Self) usize {
|
||||
return self.queSize;
|
||||
return self.que_size;
|
||||
}
|
||||
|
||||
// 判断队列是否为空
|
||||
pub fn isEmpty(self: *Self) bool {
|
||||
return self.queSize == 0;
|
||||
return self.que_size == 0;
|
||||
}
|
||||
|
||||
// 入队
|
||||
|
@ -1585,10 +1585,10 @@ comments: true
|
|||
}
|
||||
// 计算尾指针,指向队尾索引 + 1
|
||||
// 通过取余操作,实现 rear 越过数组尾部后回到头部
|
||||
var rear = (self.front + self.queSize) % self.capacity();
|
||||
var rear = (self.front + self.que_size) % self.capacity();
|
||||
// 将 num 添加至队尾
|
||||
self.nums[rear] = num;
|
||||
self.queSize += 1;
|
||||
self.que_size += 1;
|
||||
}
|
||||
|
||||
// 出队
|
||||
|
@ -1596,7 +1596,7 @@ comments: true
|
|||
var num = self.peek();
|
||||
// 队首指针向后移动一位,若越过尾部则返回到数组头部
|
||||
self.front = (self.front + 1) % self.capacity();
|
||||
self.queSize -= 1;
|
||||
self.que_size -= 1;
|
||||
return num;
|
||||
}
|
||||
|
||||
|
|
Loading…
Reference in a new issue